diff --git a/bitbake/bin/bitbake b/bitbake/bin/bitbake
index 042c9180..0b9cc629 100755
--- a/bitbake/bin/bitbake
+++ b/bitbake/bin/bitbake
@@ -25,8 +25,7 @@ except RuntimeError as exc:
 from bb import cookerdata
 from bb.main import bitbake_main, BitBakeConfigParameters, BBMainException
 
-if sys.getfilesystemencoding() != "utf-8":
-    sys.exit("Please use a locale setting which supports UTF-8 (such as LANG=en_US.UTF-8).\nPython can't change the filesystem locale after loading so we need a UTF-8 when Python starts or things won't work.")
+bb.utils.check_system_locale()
 
 __version__ = "2.0.0"
 
diff --git a/bitbake/bin/bitbake-diffsigs b/bitbake/bin/bitbake-diffsigs
index cf4cc706..fe0f33ee 100755
--- a/bitbake/bin/bitbake-diffsigs
+++ b/bitbake/bin/bitbake-diffsigs
@@ -11,6 +11,7 @@
 import os
 import sys
 import warnings
+
 warnings.simplefilter("default")
 import argparse
 import logging
@@ -27,6 +28,7 @@ logger = bb.msg.logger_create(myname)
 
 is_dump = myname == 'bitbake-dumpsig'
 
+
 def find_siginfo(tinfoil, pn, taskname, sigs=None):
     result = None
     tinfoil.set_event_mask(['bb.event.FindSigInfoResult',
@@ -52,6 +54,7 @@ def find_siginfo(tinfoil, pn, taskname, sigs=None):
         sys.exit(2)
     return result
 
+
 def find_siginfo_task(bbhandler, pn, taskname, sig1=None, sig2=None):
     """ Find the most recent signature files for the specified PN/task """
 
@@ -63,10 +66,10 @@ def find_siginfo_task(bbhandler, pn, taskname, sig1=None, sig2=None):
         if not sigfiles:
             logger.error('No sigdata files found matching %s %s matching either %s or %s' % (pn, taskname, sig1, sig2))
             sys.exit(1)
-        elif not sig1 in sigfiles:
+        elif sig1 not in sigfiles:
             logger.error('No sigdata files found matching %s %s with signature %s' % (pn, taskname, sig1))
             sys.exit(1)
-        elif not sig2 in sigfiles:
+        elif sig2 not in sigfiles:
             logger.error('No sigdata files found matching %s %s with signature %s' % (pn, taskname, sig2))
             sys.exit(1)
         latestfiles = [sigfiles[sig1], sigfiles[sig2]]
@@ -88,9 +91,9 @@ def recursecb(key, hash1, hash2):
     recout = []
     if not hashfiles:
         recout.append("Unable to find matching sigdata for %s with hashes %s or %s" % (key, hash1, hash2))
-    elif not hash1 in hashfiles:
+    elif hash1 not in hashfiles:
         recout.append("Unable to find matching sigdata for %s with hash %s" % (key, hash1))
-    elif not hash2 in hashfiles:
+    elif hash2 not in hashfiles:
         recout.append("Unable to find matching sigdata for %s with hash %s" % (key, hash2))
     else:
         out2 = bb.siggen.compare_sigfiles(hashfiles[hash1], hashfiles[hash2], recursecb, color=color)
@@ -110,36 +113,36 @@ parser.add_argument('-D', '--debug',
 
 if is_dump:
     parser.add_argument("-t", "--task",
-            help="find the signature data file for the last run of the specified task",
-            action="store", dest="taskargs", nargs=2, metavar=('recipename', 'taskname'))
+                        help="find the signature data file for the last run of the specified task",
+                        action="store", dest="taskargs", nargs=2, metavar=('recipename', 'taskname'))
 
     parser.add_argument("sigdatafile1",
-            help="Signature file to dump. Not used when using -t/--task.",
-            action="store", nargs='?', metavar="sigdatafile")
+                        help="Signature file to dump. Not used when using -t/--task.",
+                        action="store", nargs='?', metavar="sigdatafile")
 else:
     parser.add_argument('-c', '--color',
-            help='Colorize the output (where %(metavar)s is %(choices)s)',
-            choices=['auto', 'always', 'never'], default='auto', metavar='color')
+                        help='Colorize the output (where %(metavar)s is %(choices)s)',
+                        choices=['auto', 'always', 'never'], default='auto', metavar='color')
 
     parser.add_argument('-d', '--dump',
-            help='Dump the last signature data instead of comparing (equivalent to using bitbake-dumpsig)',
-            action='store_true')
+                        help='Dump the last signature data instead of comparing (equivalent to using bitbake-dumpsig)',
+                        action='store_true')
 
     parser.add_argument("-t", "--task",
-            help="find the signature data files for the last two runs of the specified task and compare them",
-            action="store", dest="taskargs", nargs=2, metavar=('recipename', 'taskname'))
+                        help="find the signature data files for the last two runs of the specified task and compare them",
+                        action="store", dest="taskargs", nargs=2, metavar=('recipename', 'taskname'))
 
     parser.add_argument("-s", "--signature",
-            help="With -t/--task, specify the signatures to look for instead of taking the last two",
-            action="store", dest="sigargs", nargs=2, metavar=('fromsig', 'tosig'))
+                        help="With -t/--task, specify the signatures to look for instead of taking the last two",
+                        action="store", dest="sigargs", nargs=2, metavar=('fromsig', 'tosig'))
 
     parser.add_argument("sigdatafile1",
-            help="First signature file to compare (or signature file to dump, if second not specified). Not used when using -t/--task.",
-            action="store", nargs='?')
+                        help="First signature file to compare (or signature file to dump, if second not specified). Not used when using -t/--task.",
+                        action="store", nargs='?')
 
     parser.add_argument("sigdatafile2",
-            help="Second signature file to compare",
-            action="store", nargs='?')
+                        help="Second signature file to compare",
+                        action="store", nargs='?')
 
 options = parser.parse_args()
 if is_dump:
@@ -157,7 +160,8 @@ if options.taskargs:
     with bb.tinfoil.Tinfoil() as tinfoil:
         tinfoil.prepare(config_only=True)
         if not options.dump and options.sigargs:
-            files = find_siginfo_task(tinfoil, options.taskargs[0], options.taskargs[1], options.sigargs[0], options.sigargs[1])
+            files = find_siginfo_task(tinfoil, options.taskargs[0], options.taskargs[1], options.sigargs[0],
+                                      options.sigargs[1])
         else:
             files = find_siginfo_task(tinfoil, options.taskargs[0], options.taskargs[1])
 
@@ -166,7 +170,8 @@ if options.taskargs:
             output = bb.siggen.dump_sigfile(files[-1])
         else:
             if len(files) < 2:
-                logger.error('Only one matching sigdata file found for the specified task (%s %s)' % (options.taskargs[0], options.taskargs[1]))
+                logger.error('Only one matching sigdata file found for the specified task (%s %s)' % (
+                    options.taskargs[0], options.taskargs[1]))
                 sys.exit(1)
 
             # Recurse into signature comparison
diff --git a/bitbake/bin/bitbake-layers b/bitbake/bin/bitbake-layers
index 449434d4..d4b1d1aa 100755
--- a/bitbake/bin/bitbake-layers
+++ b/bitbake/bin/bitbake-layers
@@ -68,11 +68,11 @@ def main():
 
         registered = False
         for plugin in plugins:
+            if hasattr(plugin, 'tinfoil_init'):
+                plugin.tinfoil_init(tinfoil)
             if hasattr(plugin, 'register_commands'):
                 registered = True
                 plugin.register_commands(subparsers)
-            if hasattr(plugin, 'tinfoil_init'):
-                plugin.tinfoil_init(tinfoil)
 
         if not registered:
             logger.error("No commands registered - missing plugins?")
diff --git a/bitbake/bin/bitbake-server b/bitbake/bin/bitbake-server
index f53f88b6..d00bb068 100755
--- a/bitbake/bin/bitbake-server
+++ b/bitbake/bin/bitbake-server
@@ -12,8 +12,9 @@ warnings.simplefilter("default")
 import logging
 sys.path.insert(0, os.path.join(os.path.dirname(os.path.dirname(sys.argv[0])), 'lib'))
 
-if sys.getfilesystemencoding() != "utf-8":
-    sys.exit("Please use a locale setting which supports UTF-8 (such as LANG=en_US.UTF-8).\nPython can't change the filesystem locale after loading so we need a UTF-8 when Python starts or things won't work.")
+import bb
+
+bb.utils.check_system_locale()
 
 # Users shouldn't be running this code directly
 if len(sys.argv) != 10 or not sys.argv[1].startswith("decafbad"):
diff --git a/bitbake/bin/bitbake-worker b/bitbake/bin/bitbake-worker
index 2f3e9f72..5e62bc20 100755
--- a/bitbake/bin/bitbake-worker
+++ b/bitbake/bin/bitbake-worker
@@ -24,8 +24,7 @@ import subprocess
 from multiprocessing import Lock
 from threading import Thread
 
-if sys.getfilesystemencoding() != "utf-8":
-    sys.exit("Please use a locale setting which supports UTF-8 (such as LANG=en_US.UTF-8).\nPython can't change the filesystem locale after loading so we need a UTF-8 when Python starts or things won't work.")
+bb.utils.check_system_locale()
 
 # Users shouldn't be running this code directly
 if len(sys.argv) != 2 or not sys.argv[1].startswith("decafbad"):
diff --git a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst
index 9c269ca8..519aec9a 100644
--- a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst
+++ b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst
@@ -424,8 +424,8 @@ This fetcher supports the following parameters:
 
 -  *"nobranch":* Tells the fetcher to not check the SHA validation for
    the branch when set to "1". The default is "0". Set this option for
-   the recipe that refers to the commit that is valid for a tag instead
-   of the branch.
+   the recipe that refers to the commit that is valid for any namespace
+   (branch, tag, ...) instead of the branch.
 
 -  *"bareclone":* Tells the fetcher to clone a bare clone into the
    destination directory without checking out a working tree. Only the
diff --git a/bitbake/lib/bb/cookerdata.py b/bitbake/lib/bb/cookerdata.py
index fe5696c7..ec3741cc 100644
--- a/bitbake/lib/bb/cookerdata.py
+++ b/bitbake/lib/bb/cookerdata.py
@@ -160,12 +160,7 @@ def catch_parse_error(func):
     def wrapped(fn, *args):
         try:
             return func(fn, *args)
-        except IOError as exc:
-            import traceback
-            parselog.critical(traceback.format_exc())
-            parselog.critical("Unable to parse %s: %s" % (fn, exc))
-            raise bb.BBHandledException()
-        except bb.data_smart.ExpansionError as exc:
+        except Exception as exc:
             import traceback
 
             bbdir = os.path.dirname(__file__) + os.sep
@@ -177,9 +172,6 @@ def catch_parse_error(func):
                     break
             parselog.critical("Unable to parse %s" % fn, exc_info=(exc_class, exc, tb))
             raise bb.BBHandledException()
-        except bb.parse.ParseError as exc:
-            parselog.critical(str(exc))
-            raise bb.BBHandledException()
     return wrapped
 
 @catch_parse_error
@@ -301,14 +293,9 @@ class CookerDataBuilder(object):
                 bb.event.fire(bb.event.MultiConfigParsed(self.mcdata), self.data)
 
             self.data_hash = data_hash.hexdigest()
-        except (SyntaxError, bb.BBHandledException):
-            raise bb.BBHandledException()
         except bb.data_smart.ExpansionError as e:
             logger.error(str(e))
             raise bb.BBHandledException()
-        except Exception:
-            logger.exception("Error parsing configuration files")
-            raise bb.BBHandledException()
 
 
         # Handle obsolete variable names
@@ -435,7 +422,7 @@ class CookerDataBuilder(object):
                 msg += (" and bitbake did not find a conf/bblayers.conf file in"
                         " the expected location.\nMaybe you accidentally"
                         " invoked bitbake from the wrong directory?")
-            raise SystemExit(msg)
+            bb.fatal(msg)
 
         if not data.getVar("TOPDIR"):
             data.setVar("TOPDIR", os.path.abspath(os.getcwd()))
diff --git a/bitbake/lib/bb/fetch2/git.py b/bitbake/lib/bb/fetch2/git.py
index f0df6fb6..4d6e57ad 100644
--- a/bitbake/lib/bb/fetch2/git.py
+++ b/bitbake/lib/bb/fetch2/git.py
@@ -44,7 +44,8 @@ Supported SRC_URI options are:
 
 - nobranch
    Don't check the SHA validation for branch. set this option for the recipe
-   referring to commit which is valid in tag instead of branch.
+   referring to commit which is valid in any namespace (branch, tag, ...)
+   instead of branch.
    The default is "0", set nobranch=1 if needed.
 
 - usehead
@@ -358,9 +359,13 @@ class Git(FetchMethod):
 
         # If the repo still doesn't exist, fallback to cloning it
         if not os.path.exists(ud.clonedir):
-            # We do this since git will use a "-l" option automatically for local urls where possible
+            # We do this since git will use a "-l" option automatically for local urls where possible,
+            # but it doesn't work when git/objects is a symlink, only works when it is a directory.
             if repourl.startswith("file://"):
-                repourl = repourl[7:]
+                repourl_path = repourl[7:]
+                objects = os.path.join(repourl_path, 'objects')
+                if os.path.isdir(objects) and not os.path.islink(objects):
+                    repourl = repourl_path
             clone_cmd = "LANG=C %s clone --bare --mirror %s %s --progress" % (ud.basecmd, shlex.quote(repourl), ud.clonedir)
             if ud.proto.lower() != 'file':
                 bb.fetch2.check_network_access(d, clone_cmd, ud.url)
@@ -374,7 +379,11 @@ class Git(FetchMethod):
               runfetchcmd("%s remote rm origin" % ud.basecmd, d, workdir=ud.clonedir)
 
             runfetchcmd("%s remote add --mirror=fetch origin %s" % (ud.basecmd, shlex.quote(repourl)), d, workdir=ud.clonedir)
-            fetch_cmd = "LANG=C %s fetch -f --progress %s refs/*:refs/*" % (ud.basecmd, shlex.quote(repourl))
+
+            if ud.nobranch:
+                fetch_cmd = "LANG=C %s fetch -f --progress %s refs/*:refs/*" % (ud.basecmd, shlex.quote(repourl))
+            else:
+                fetch_cmd = "LANG=C %s fetch -f --progress %s refs/heads/*:refs/heads/* refs/tags/*:refs/tags/*" % (ud.basecmd, shlex.quote(repourl))
             if ud.proto.lower() != 'file':
                 bb.fetch2.check_network_access(d, fetch_cmd, ud.url)
             progresshandler = GitProgressHandler(d)
@@ -731,7 +740,7 @@ class Git(FetchMethod):
         Compute the HEAD revision for the url
         """
         if not d.getVar("__BBSEENSRCREV"):
-            raise bb.fetch2.FetchError("Recipe uses a floating tag/branch without a fixed SRCREV yet doesn't call bb.fetch2.get_srcrev() (use SRCPV in PV for OE).")
+            raise bb.fetch2.FetchError("Recipe uses a floating tag/branch '%s' for repo '%s' without a fixed SRCREV yet doesn't call bb.fetch2.get_srcrev() (use SRCPV in PV for OE)." % (ud.unresolvedrev[name], ud.host+ud.path))
 
         # Ensure we mark as not cached
         bb.fetch2.get_autorev(d)
diff --git a/bitbake/lib/bb/fetch2/gitsm.py b/bitbake/lib/bb/fetch2/gitsm.py
index 25d5db0e..c5f7c03c 100644
--- a/bitbake/lib/bb/fetch2/gitsm.py
+++ b/bitbake/lib/bb/fetch2/gitsm.py
@@ -115,7 +115,7 @@ class GitSM(Git):
                     # This has to be a file reference
                     proto = "file"
                     url = "gitsm://" + uris[module]
-            if "{}{}".format(ud.host, ud.path) in url:
+            if url.endswith("{}{}".format(ud.host, ud.path)):
                 raise bb.fetch2.FetchError("Submodule refers to the parent repository. This will cause deadlock situation in current version of Bitbake." \
                                            "Consider using git fetcher instead.")
 
diff --git a/bitbake/lib/bb/runqueue.py b/bitbake/lib/bb/runqueue.py
index 48e25401..56952070 100644
--- a/bitbake/lib/bb/runqueue.py
+++ b/bitbake/lib/bb/runqueue.py
@@ -1974,11 +1974,19 @@ class RunQueueExecute:
                 self.setbuildable(revdep)
                 logger.debug("Marking task %s as buildable", revdep)
 
-        for t in self.sq_deferred.copy():
+        found = None
+        for t in sorted(self.sq_deferred.copy()):
             if self.sq_deferred[t] == task:
-                logger.debug2("Deferred task %s now buildable" % t)
-                del self.sq_deferred[t]
-                update_scenequeue_data([t], self.sqdata, self.rqdata, self.rq, self.cooker, self.stampcache, self, summary=False)
+                # Allow the next deferred task to run. Any other deferred tasks should be deferred after that task.
+                # We shouldn't allow all to run at once as it is prone to races.
+                if not found:
+                    bb.note("Deferred task %s now buildable" % t)
+                    del self.sq_deferred[t]
+                    update_scenequeue_data([t], self.sqdata, self.rqdata, self.rq, self.cooker, self.stampcache, self, summary=False)
+                    found = t
+                else:
+                    bb.note("Deferring %s after %s" % (t, found))
+                    self.sq_deferred[t] = found
 
     def task_complete(self, task):
         self.stats.taskCompleted()
@@ -2489,17 +2497,6 @@ class RunQueueExecute:
                 self.sq_buildable.remove(tid)
             if tid in self.sq_running:
                 self.sq_running.remove(tid)
-            harddepfail = False
-            for t in self.sqdata.sq_harddeps:
-                if tid in self.sqdata.sq_harddeps[t] and t in self.scenequeue_notcovered:
-                    harddepfail = True
-                    break
-            if not harddepfail and self.sqdata.sq_revdeps[tid].issubset(self.scenequeue_covered | self.scenequeue_notcovered):
-                if tid not in self.sq_buildable:
-                    self.sq_buildable.add(tid)
-            if not self.sqdata.sq_revdeps[tid]:
-                self.sq_buildable.add(tid)
-
             if tid in self.sqdata.outrightfail:
                 self.sqdata.outrightfail.remove(tid)
             if tid in self.scenequeue_notcovered:
@@ -2518,21 +2515,36 @@ class RunQueueExecute:
             if tid in self.build_stamps:
                 del self.build_stamps[tid]
 
-            update_tasks.append((tid, harddepfail, tid in self.sqdata.valid))
+            update_tasks.append(tid)
+
+        update_tasks2 = []
+        for tid in update_tasks:
+            harddepfail = False
+            for t in self.sqdata.sq_harddeps:
+                if tid in self.sqdata.sq_harddeps[t] and t in self.scenequeue_notcovered:
+                    harddepfail = True
+                    break
+            if not harddepfail and self.sqdata.sq_revdeps[tid].issubset(self.scenequeue_covered | self.scenequeue_notcovered):
+                if tid not in self.sq_buildable:
+                    self.sq_buildable.add(tid)
+            if not self.sqdata.sq_revdeps[tid]:
+                self.sq_buildable.add(tid)
+
+            update_tasks2.append((tid, harddepfail, tid in self.sqdata.valid))
 
-        if update_tasks:
+        if update_tasks2:
             self.sqdone = False
             for mc in sorted(self.sqdata.multiconfigs):
-                for tid in sorted([t[0] for t in update_tasks]):
+                for tid in sorted([t[0] for t in update_tasks2]):
                     if mc_from_tid(tid) != mc:
                         continue
                     h = pending_hash_index(tid, self.rqdata)
                     if h in self.sqdata.hashes and tid != self.sqdata.hashes[h]:
                         self.sq_deferred[tid] = self.sqdata.hashes[h]
                         bb.note("Deferring %s after %s" % (tid, self.sqdata.hashes[h]))
-            update_scenequeue_data([t[0] for t in update_tasks], self.sqdata, self.rqdata, self.rq, self.cooker, self.stampcache, self, summary=False)
+            update_scenequeue_data([t[0] for t in update_tasks2], self.sqdata, self.rqdata, self.rq, self.cooker, self.stampcache, self, summary=False)
 
-        for (tid, harddepfail, origvalid) in update_tasks:
+        for (tid, harddepfail, origvalid) in update_tasks2:
             if tid in self.sqdata.valid and not origvalid:
                 hashequiv_logger.verbose("Setscene task %s became valid" % tid)
             if harddepfail:
diff --git a/bitbake/lib/bb/siggen.py b/bitbake/lib/bb/siggen.py
index 9a20fc8e..0a9ce0ed 100644
--- a/bitbake/lib/bb/siggen.py
+++ b/bitbake/lib/bb/siggen.py
@@ -329,19 +329,19 @@ class SignatureGeneratorBasic(SignatureGenerator):
 
         data = self.basehash[tid]
         for dep in self.runtaskdeps[tid]:
-            data = data + self.get_unihash(dep)
+            data += self.get_unihash(dep)
 
         for (f, cs) in self.file_checksum_values[tid]:
             if cs:
                 if "/./" in f:
-                    data = data + "./" + f.split("/./")[1]
-                data = data + cs
+                    data += "./" + f.split("/./")[1]
+                data += cs
 
         if tid in self.taints:
             if self.taints[tid].startswith("nostamp:"):
-                data = data + self.taints[tid][8:]
+                data += self.taints[tid][8:]
             else:
-                data = data + self.taints[tid]
+                data += self.taints[tid]
 
         h = hashlib.sha256(data.encode("utf-8")).hexdigest()
         self.taskhash[tid] = h
@@ -1028,6 +1028,7 @@ def compare_sigfiles(a, b, recursecb=None, color=False, collapsed=False):
                             # If a dependent hash changed, might as well print the line above and then defer to the changes in
                             # that hash since in all likelyhood, they're the same changes this task also saw.
                             output = [output[-1]] + recout
+                            break
 
     a_taint = a_data.get('taint', None)
     b_taint = b_data.get('taint', None)
diff --git a/bitbake/lib/bb/utils.py b/bitbake/lib/bb/utils.py
index 92d44c52..3f7f82d1 100644
--- a/bitbake/lib/bb/utils.py
+++ b/bitbake/lib/bb/utils.py
@@ -13,6 +13,7 @@ import errno
 import logging
 import bb
 import bb.msg
+import locale
 import multiprocessing
 import fcntl
 import importlib
@@ -545,7 +546,12 @@ def md5_file(filename):
     Return the hex string representation of the MD5 checksum of filename.
     """
     import hashlib
-    return _hasher(hashlib.new('MD5', usedforsecurity=False), filename)
+    try:
+        sig = hashlib.new('MD5', usedforsecurity=False)
+    except TypeError:
+        # Some configurations don't appear to support two arguments
+        sig = hashlib.new('MD5')
+    return _hasher(sig, filename)
 
 def sha256_file(filename):
     """
@@ -601,6 +607,21 @@ def preserved_envvars():
     ]
     return v + preserved_envvars_exported()
 
+def check_system_locale():
+    """Make sure the required system locale are available and configured"""
+    default_locale = locale.getlocale(locale.LC_CTYPE)
+
+    try:
+        locale.setlocale(locale.LC_CTYPE, ("en_US", "UTF-8"))
+    except:
+        sys.exit("Please make sure locale 'en_US.UTF-8' is available on your system")
+    else:
+        locale.setlocale(locale.LC_CTYPE, default_locale)
+
+    if sys.getfilesystemencoding() != "utf-8":
+        sys.exit("Please use a locale setting which supports UTF-8 (such as LANG=en_US.UTF-8).\n"
+                 "Python can't change the filesystem locale after loading so we need a UTF-8 when Python starts or things won't work.")
+
 def filter_environment(good_vars):
     """
     Create a pristine environment for bitbake. This will remove variables that
@@ -985,6 +1006,9 @@ def to_boolean(string, default=None):
     if not string:
         return default
 
+    if isinstance(string, int):
+        return string != 0
+
     normalized = string.lower()
     if normalized in ("y", "yes", "1", "true"):
         return True
@@ -1635,23 +1659,20 @@ def disable_network(uid=None, gid=None):
 
 def export_proxies(d):
     """ export common proxies variables from datastore to environment """
-    import os
 
     variables = ['http_proxy', 'HTTP_PROXY', 'https_proxy', 'HTTPS_PROXY',
                     'ftp_proxy', 'FTP_PROXY', 'no_proxy', 'NO_PROXY',
-                    'GIT_PROXY_COMMAND']
-    exported = False
+                    'GIT_PROXY_COMMAND', 'SSL_CERT_FILE', 'SSL_CERT_DIR']
 
-    for v in variables:
-        if v in os.environ.keys():
-            exported = True
-        else:
-            v_proxy = d.getVar(v)
-            if v_proxy is not None:
-                os.environ[v] = v_proxy
-                exported = True
+    origenv = d.getVar("BB_ORIGENV")
+
+    for name in variables:
+        value = d.getVar(name)
+        if not value and origenv:
+            value = origenv.getVar(name)
+        if value:
+            os.environ[name] = value
 
-    return exported
 
 
 def load_plugins(logger, plugins, pluginpath):
diff --git a/bitbake/lib/ply/yacc.py b/bitbake/lib/ply/yacc.py
index 767c4e46..381b50cf 100644
--- a/bitbake/lib/ply/yacc.py
+++ b/bitbake/lib/ply/yacc.py
@@ -2798,7 +2798,14 @@ class ParserReflect(object):
     def signature(self):
         try:
             import hashlib
+        except ImportError:
+            raise RuntimeError("Unable to import hashlib")
+        try:
             sig = hashlib.new('MD5', usedforsecurity=False)
+        except TypeError:
+            # Some configurations don't appear to support two arguments
+            sig = hashlib.new('MD5')
+        try:
             if self.start:
                 sig.update(self.start.encode('latin-1'))
             if self.prec:
