gclient_scm: Make calls to "git merge-base" non-fatal.

gclient_scm.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Gclient-specific SCM-specific operations."""
 
 from __future__ import print_function
 
 import errno
 import logging
@@ skipping 274 matching lines @@
     return self._Capture(['log', '-n', '1', '--format=%ai'])
 
   @staticmethod
   def cleanup(options, args, file_list):
     """'Cleanup' the repo.
 
     There's no real git equivalent for the svn cleanup command, do a no-op.
     """
 
   def diff(self, options, _args, _file_list):
-    merge_base = self._Capture(['merge-base', 'HEAD', self.remote])
-    self._Run(['diff', merge_base], options)
+    try:
+      merge_base = [self._Capture(['merge-base', 'HEAD', self.remote])]
+    except subprocess2.CalledProcessError:
+      merge_base = []
+    self._Run(['diff'] + merge_base, options)
 
   def pack(self, _options, _args, _file_list):
     """Generates a patch file which can be applied to the root of the
     repository.
 
     The patch file is generated from a diff of the merge base of HEAD and
     its upstream branch.
     """
-    merge_base = self._Capture(['merge-base', 'HEAD', self.remote])
+    try:
+      merge_base = [self._Capture(['merge-base', 'HEAD', self.remote])]
+    except subprocess2.CalledProcessError:
+      merge_base = []
     gclient_utils.CheckCallAndFilter(
-        ['git', 'diff', merge_base],
+        ['git', 'diff'] + merge_base,
         cwd=self.checkout_path,
         filter_fn=GitDiffFilterer(self.relpath, print_func=self.Print).Filter)
 
   def _FetchAndReset(self, revision, file_list, options):
     """Equivalent to git fetch; git reset."""
     quiet = []
     if not options.verbose:
       quiet = ['--quiet']
     self._UpdateBranchHeads(options, fetch=False)
 
@@ skipping 460 matching lines @@
 
   def runhooks(self, options, args, file_list):
     self.status(options, args, file_list)
 
   def status(self, options, _args, file_list):
     """Display status information."""
     if not os.path.isdir(self.checkout_path):
       self.Print('________ couldn\'t run status in %s:\n'
                  'The directory does not exist.' % self.checkout_path)
     else:
-      merge_base = self._Capture(['merge-base', 'HEAD', self.remote])
-      self._Run(['diff', '--name-status', merge_base], options,
+      try:
+        merge_base = [self._Capture(['merge-base', 'HEAD', self.remote])]
+      except subprocess2.CalledProcessError:
+        merge_base = []
+      self._Run(['diff', '--name-status'] + merge_base, options,
                 stdout=self.out_fh)
       if file_list is not None:
-        files = self._Capture(['diff', '--name-only', merge_base]).split()
+        files = self._Capture(['diff', '--name-only'] + merge_base).split()
         file_list.extend([os.path.join(self.checkout_path, f) for f in files])
 
   def GetUsableRev(self, rev, options):
     """Finds a useful revision for this repository.
 
     If SCM is git-svn and the head revision is less than |rev|, git svn fetch
     will be called on the source."""
     sha1 = None
     if not os.path.isdir(self.checkout_path):
       raise NoUsableRevError(
@@ skipping 915 matching lines @@
       new_command.append('--force')
       if command[0] != 'checkout' and scm.SVN.AssertVersion('1.6')[0]:
         new_command.extend(('--accept', 'theirs-conflict'))
     elif options.manually_grab_svn_rev:
       new_command.append('--force')
       if command[0] != 'checkout' and scm.SVN.AssertVersion('1.6')[0]:
         new_command.extend(('--accept', 'postpone'))
     elif command[0] != 'checkout' and scm.SVN.AssertVersion('1.6')[0]:
       new_command.extend(('--accept', 'postpone'))
     return new_command