diff --git a/.flake8 b/.flake8
new file mode 100644
index 0000000..45ab656
--- /dev/null
+++ b/.flake8
@@ -0,0 +1,3 @@
+[flake8]
+max-line-length=80
+ignore=E111,E114,E402
diff --git a/.mailmap b/.mailmap
index f070b49..eb64bd2 100644
--- a/.mailmap
+++ b/.mailmap
@@ -1,8 +1,11 @@
 Anthony Newnam <anthony.newnam@garmin.com>    Anthony <anthony@bnovc.com>
-Shawn Pearce <sop@google.com>                 Shawn O. Pearce <sop@google.com>
+Hu Xiuyun <xiuyun.hu@hisilicon.com>           Hu xiuyun <xiuyun.hu@hisilicon.com>
+Hu Xiuyun <xiuyun.hu@hisilicon.com>           Hu Xiuyun <clouds08@qq.com>
+Jelly Chen <chenguodong@huawei.com>           chenguodong <chenguodong@huawei.com>
 Jia Bi <bijia@xiaomi.com>                     bijia <bijia@xiaomi.com>
 JoonCheol Park <jooncheol@gmail.com>          Jooncheol Park <jooncheol@gmail.com>
 Sergii Pylypenko <x.pelya.x@gmail.com>        pelya <x.pelya.x@gmail.com>
+Shawn Pearce <sop@google.com>                 Shawn O. Pearce <sop@google.com>
 Ulrik Sjölin <ulrik.sjolin@sonyericsson.com>  Ulrik Sjolin <ulrik.sjolin@gmail.com>
 Ulrik Sjölin <ulrik.sjolin@sonyericsson.com>  Ulrik Sjolin <ulrik.sjolin@sonyericsson.com>
 Ulrik Sjölin <ulrik.sjolin@sonyericsson.com>  Ulrik Sjölin <ulrik.sjolin@sonyericsson.com>
diff --git a/.pylintrc b/.pylintrc
deleted file mode 100644
index 413d66a..0000000
--- a/.pylintrc
+++ /dev/null
@@ -1,298 +0,0 @@
-# lint Python modules using external checkers.
-#
-# This is the main checker controling the other ones and the reports
-# generation. It is itself both a raw checker and an astng checker in order
-# to:
-# * handle message activation / deactivation at the module level
-# * handle some basic but necessary stats'data (number of classes, methods...)
-#
-[MASTER]
-
-# Specify a configuration file.
-#rcfile=
-
-# Python code to execute, usually for sys.path manipulation such as
-# pygtk.require().
-#init-hook=
-
-# Profiled execution.
-profile=no
-
-# Add <file or directory> to the black list. It should be a base name, not a
-# path. You may set this option multiple times.
-ignore=SVN
-
-# Pickle collected data for later comparisons.
-persistent=yes
-
-# Set the cache size for astng objects.
-cache-size=500
-
-# List of plugins (as comma separated values of python modules names) to load,
-# usually to register additional checkers.
-load-plugins=
-
-
-[MESSAGES CONTROL]
-
-# Enable only checker(s) with the given id(s). This option conflicts with the
-# disable-checker option
-#enable-checker=
-
-# Enable all checker(s) except those with the given id(s). This option
-# conflicts with the enable-checker option
-#disable-checker=
-
-# Enable all messages in the listed categories.
-#enable-msg-cat=
-
-# Disable all messages in the listed categories.
-#disable-msg-cat=
-
-# Enable the message(s) with the given id(s).
-enable=RP0004
-
-# Disable the message(s) with the given id(s).
-disable=C0326,R0903,R0912,R0913,R0914,R0915,W0141,C0111,C0103,W0603,W0703,R0911,C0301,C0302,R0902,R0904,W0142,W0212,E1101,E1103,R0201,W0201,W0122,W0232,RP0001,RP0003,RP0101,RP0002,RP0401,RP0701,RP0801,F0401,E0611,R0801,I0011
-
-[REPORTS]
-
-# set the output format. Available formats are text, parseable, colorized, msvs
-# (visual studio) and html
-output-format=text
-
-# Put messages in a separate file for each module / package specified on the
-# command line instead of printing them on stdout. Reports (if any) will be
-# written in a file name "pylint_global.[txt|html]".
-files-output=no
-
-# Tells whether to display a full report or only the messages
-reports=yes
-
-# Python expression which should return a note less than 10 (10 is the highest
-# note).You have access to the variables errors warning, statement which
-# respectivly contain the number of errors / warnings messages and the total
-# number of statements analyzed. This is used by the global evaluation report
-# (R0004).
-evaluation=10.0 - ((float(5 * error + warning + refactor + convention) / statement) * 10)
-
-# Add a comment according to your evaluation note. This is used by the global
-# evaluation report (R0004).
-comment=no
-
-# checks for
-# * unused variables / imports
-# * undefined variables
-# * redefinition of variable from builtins or from an outer scope
-# * use of variable before assigment
-#
-[VARIABLES]
-
-# Tells whether we should check for unused import in __init__ files.
-init-import=no
-
-# A regular expression matching names used for dummy variables (i.e. not used).
-dummy-variables-rgx=_|dummy
-
-# List of additional names supposed to be defined in builtins. Remember that
-# you should avoid to define new builtins when possible.
-additional-builtins=
-
-
-# try to find bugs in the code using type inference
-#
-[TYPECHECK]
-
-# Tells whether missing members accessed in mixin class should be ignored. A
-# mixin class is detected if its name ends with "mixin" (case insensitive).
-ignore-mixin-members=yes
-
-# List of classes names for which member attributes should not be checked
-# (useful for classes with attributes dynamicaly set).
-ignored-classes=SQLObject
-
-# When zope mode is activated, consider the acquired-members option to ignore
-# access to some undefined attributes.
-zope=no
-
-# List of members which are usually get through zope's acquisition mecanism and
-# so shouldn't trigger E0201 when accessed (need zope=yes to be considered).
-acquired-members=REQUEST,acl_users,aq_parent
-
-
-# checks for :
-# * doc strings
-# * modules / classes / functions / methods / arguments / variables name
-# * number of arguments, local variables, branchs, returns and statements in
-# functions, methods
-# * required module attributes
-# * dangerous default values as arguments
-# * redefinition of function / method / class
-# * uses of the global statement
-#
-[BASIC]
-
-# Required attributes for module, separated by a comma
-required-attributes=
-
-# Regular expression which should only match functions or classes name which do
-# not require a docstring
-no-docstring-rgx=_main|__.*__
-
-# Regular expression which should only match correct module names
-module-rgx=(([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+))$
-
-# Regular expression which should only match correct module level names
-const-rgx=(([A-Z_][A-Z1-9_]*)|(__.*__))|(log)$
-
-# Regular expression which should only match correct class names
-class-rgx=[A-Z_][a-zA-Z0-9]+$
-
-# Regular expression which should only match correct function names
-function-rgx=[a-z_][a-z0-9_]{2,30}$
-
-# Regular expression which should only match correct method names
-method-rgx=[a-z_][a-z0-9_]{2,30}$
-
-# Regular expression which should only match correct instance attribute names
-attr-rgx=[a-z_][a-z0-9_]{2,30}$
-
-# Regular expression which should only match correct argument names
-argument-rgx=[a-z_][a-z0-9_]{2,30}$
-
-# Regular expression which should only match correct variable names
-variable-rgx=[a-z_][a-z0-9_]{2,30}$
-
-# Regular expression which should only match correct list comprehension /
-# generator expression variable names
-inlinevar-rgx=[A-Za-z_][A-Za-z0-9_]*$
-
-# Good variable names which should always be accepted, separated by a comma
-good-names=i,j,k,ex,Run,_,e,d1,d2,v,f,l,d
-
-# Bad variable names which should always be refused, separated by a comma
-bad-names=foo,bar,baz,toto,tutu,tata
-
-# List of builtins function names that should not be used, separated by a comma
-bad-functions=map,filter,apply,input
-
-
-# checks for sign of poor/misdesign:
-# * number of methods, attributes, local variables...
-# * size, complexity of functions, methods
-#
-[DESIGN]
-
-# Maximum number of arguments for function / method
-max-args=5
-
-# Maximum number of locals for function / method body
-max-locals=15
-
-# Maximum number of return / yield for function / method body
-max-returns=6
-
-# Maximum number of branch for function / method body
-max-branchs=12
-
-# Maximum number of statements in function / method body
-max-statements=50
-
-# Maximum number of parents for a class (see R0901).
-max-parents=7
-
-# Maximum number of attributes for a class (see R0902).
-max-attributes=20
-
-# Minimum number of public methods for a class (see R0903).
-min-public-methods=2
-
-# Maximum number of public methods for a class (see R0904).
-max-public-methods=30
-
-
-# checks for
-# * external modules dependencies
-# * relative / wildcard imports
-# * cyclic imports
-# * uses of deprecated modules
-#
-[IMPORTS]
-
-# Deprecated modules which should not be used, separated by a comma
-deprecated-modules=regsub,string,TERMIOS,Bastion,rexec
-
-# Create a graph of every (i.e. internal and external) dependencies in the
-# given file (report R0402 must not be disabled)
-import-graph=
-
-# Create a graph of external dependencies in the given file (report R0402 must
-# not be disabled)
-ext-import-graph=
-
-# Create a graph of internal dependencies in the given file (report R0402 must
-# not be disabled)
-int-import-graph=
-
-
-# checks for :
-# * methods without self as first argument
-# * overridden methods signature
-# * access only to existant members via self
-# * attributes not defined in the __init__ method
-# * supported interfaces implementation
-# * unreachable code
-#
-[CLASSES]
-
-# List of interface methods to ignore, separated by a comma. This is used for
-# instance to not check methods defines in Zope's Interface base class.
-ignore-iface-methods=isImplementedBy,deferred,extends,names,namesAndDescriptions,queryDescriptionFor,getBases,getDescriptionFor,getDoc,getName,getTaggedValue,getTaggedValueTags,isEqualOrExtendedBy,setTaggedValue,isImplementedByInstancesOf,adaptWith,is_implemented_by
-
-# List of method names used to declare (i.e. assign) instance attributes.
-defining-attr-methods=__init__,__new__,setUp
-
-
-# checks for similarities and duplicated code. This computation may be
-# memory / CPU intensive, so you should disable it if you experiments some
-# problems.
-#
-[SIMILARITIES]
-
-# Minimum lines number of a similarity.
-min-similarity-lines=4
-
-# Ignore comments when computing similarities.
-ignore-comments=yes
-
-# Ignore docstrings when computing similarities.
-ignore-docstrings=yes
-
-
-# checks for:
-# * warning notes in the code like FIXME, XXX
-# * PEP 263: source code with non ascii character but no encoding declaration
-#
-[MISCELLANEOUS]
-
-# List of note tags to take in consideration, separated by a comma.
-notes=FIXME,XXX,TODO
-
-
-# checks for :
-# * unauthorized constructions
-# * strict indentation
-# * line length
-# * use of <> instead of !=
-#
-[FORMAT]
-
-# Maximum number of characters on a single line.
-max-line-length=80
-
-# Maximum number of lines in a module
-max-module-lines=1000
-
-# String used as indentation unit. This is usually "    " (4 spaces) or "\t" (1
-# tab).  In repo it is 2 spaces.
-indent-string='  '
diff --git a/SUBMITTING_PATCHES.md b/SUBMITTING_PATCHES.md
index 085ae06..07f7661 100644
--- a/SUBMITTING_PATCHES.md
+++ b/SUBMITTING_PATCHES.md
@@ -2,7 +2,7 @@
 
  - Make small logical changes.
  - Provide a meaningful commit message.
- - Check for coding errors with pylint
+ - Check for coding errors and style nits with pyflakes and flake8
  - Make sure all code is under the Apache License, 2.0.
  - Publish your changes for review.
  - Make corrections if requested.
@@ -36,12 +36,32 @@
 probably need to split up your commit to finer grained pieces.
 
 
-## Check for coding errors with pylint
+## Check for coding errors and style nits with pyflakes and flake8
 
-Run pylint on changed modules using the provided configuration:
+### Coding errors
 
-    pylint --rcfile=.pylintrc file.py
+Run `pyflakes` on changed modules:
 
+    pyflakes file.py
+
+Ideally there should be no new errors or warnings introduced.
+
+### Style violations
+
+Run `flake8` on changes modules:
+
+    flake8 file.py
+
+Note that repo generally follows [Google's python style guide]
+(https://google.github.io/styleguide/pyguide.html) rather than [PEP 8]
+(https://www.python.org/dev/peps/pep-0008/), so it's possible that
+the output of `flake8` will be quite noisy. It's not mandatory to
+avoid all warnings, but at least the maximum line length should be
+followed.
+
+If there are many occurrences of the same warning that cannot be
+avoided without going against the Google style guide, these may be
+suppressed in the included `.flake8` file.
 
 ## Check the license
 
diff --git a/project.py b/project.py
index 46e06bf..0a86a71 100644
--- a/project.py
+++ b/project.py
@@ -1834,7 +1834,7 @@
                            objdir=objdir,
                            worktree=worktree,
                            relpath=relpath,
-                           revisionExpr=self.revisionExpr,
+                           revisionExpr=rev,
                            revisionId=rev,
                            rebase=self.rebase,
                            groups=self.groups,
diff --git a/repo b/repo
index f9eb9e8..acaa9c4 100755
--- a/repo
+++ b/repo
@@ -27,6 +27,9 @@
 
 # increment this if the MAINTAINER_KEYS block is modified
 KEYRING_VERSION = (1, 2)
+
+# Each individual key entry is created by using:
+# gpg --armor --export keyid
 MAINTAINER_KEYS = """
 
      Repo Maintainer <repo@android.kernel.org>
diff --git a/subcmds/start.py b/subcmds/start.py
index d1430a9..290b689 100644
--- a/subcmds/start.py
+++ b/subcmds/start.py
@@ -54,8 +54,7 @@
     if not opt.all:
       projects = args[1:]
       if len(projects) < 1:
-        print("error: at least one project must be specified", file=sys.stderr)
-        sys.exit(1)
+        projects = ['.',]  # start it in the local project by default
 
     all_projects = self.GetProjects(projects,
                                     missing_ok=bool(self.gitc_manifest))
diff --git a/subcmds/sync.py b/subcmds/sync.py
index 9124a65..ecf2ffc 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -397,9 +397,12 @@
     return fetched
 
   def _GCProjects(self, projects):
-    gitdirs = {}
+    gc_gitdirs = {}
     for project in projects:
-      gitdirs[project.gitdir] = project.bare_git
+      if len(project.manifest.GetProjectsWithName(project.name)) > 1:
+        print('Shared project %s found, disabling pruning.' % project.name)
+        project.bare_git.config('--replace-all', 'gc.pruneExpire', 'never')
+      gc_gitdirs[project.gitdir] = project.bare_git
 
     has_dash_c = git_require((1, 7, 2))
     if multiprocessing and has_dash_c:
@@ -409,7 +412,7 @@
     jobs = min(self.jobs, cpu_count)
 
     if jobs < 2:
-      for bare_git in gitdirs.values():
+      for bare_git in gc_gitdirs.values():
         bare_git.gc('--auto')
       return
 
@@ -431,7 +434,7 @@
       finally:
         sem.release()
 
-    for bare_git in gitdirs.values():
+    for bare_git in gc_gitdirs.values():
       if err_event.isSet():
         break
       sem.acquire()
diff --git a/subcmds/upload.py b/subcmds/upload.py
index 4b05f1e..1172dad 100644
--- a/subcmds/upload.py
+++ b/subcmds/upload.py
@@ -454,7 +454,11 @@
       if avail:
         pending.append((project, avail))
 
-    if pending and (not opt.bypass_hooks):
+    if not pending:
+      print("no branches ready for upload", file=sys.stderr)
+      return
+
+    if not opt.bypass_hooks:
       hook = RepoHook('pre-upload', self.manifest.repo_hooks_project,
                       self.manifest.topdir,
                       self.manifest.manifestProject.GetRemote('origin').url,
@@ -474,9 +478,7 @@
       cc = _SplitEmails(opt.cc)
     people = (reviewers, cc)
 
-    if not pending:
-      print("no branches ready for upload", file=sys.stderr)
-    elif len(pending) == 1 and len(pending[0][1]) == 1:
+    if len(pending) == 1 and len(pending[0][1]) == 1:
       self._SingleBranch(opt, pending[0][1][0], people)
     else:
       self._MultipleBranches(opt, pending, people)