Make gclient ready for the Blink (DEPS to main project) transition

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 372 matching lines @@
       # always specify branches as they are in the upstream repo.
       rev_type = "branch"
     else:
       # hash is also a tag, only make a distinction at checkout
       rev_type = "hash"
 
     mirror = self._GetMirror(url, options)
     if mirror:
       url = mirror.mirror_path
 
+    # If we are going to introduce a new project, there is a possibility that
+    # we are syncing back to a state where the project was originally a
+    # sub-project rolled by DEPS (realistic case: crossing the Blink merge point
+    # syncing backwards, when Blink was a DEPS entry and not part of src.git).
+    # In such case, we might have a backup of the former .git folder, which can
+    # be used to avoid re-fetching the entire repo again (useful for bisects).
+    backup_dir = self.GetGitBackupDirPath()
+    target_dir = os.path.join(self.checkout_path, '.git')
+    if os.path.exists(backup_dir) and not os.path.exists(target_dir):
+      gclient_utils.safe_makedirs(self.checkout_path)
+      os.rename(backup_dir, target_dir)
+      # Reset to a clean state
+      self._Run(['reset', '--hard', 'HEAD'], options)
+
     if (not os.path.exists(self.checkout_path) or
         (os.path.isdir(self.checkout_path) and
          not os.path.exists(os.path.join(self.checkout_path, '.git')))):
       if mirror:
         self._UpdateMirror(mirror, options)
       try:
         self._Clone(revision, url, options)
       except subprocess2.CalledProcessError:
         self._DeleteOrMove(options.force)
         self._Clone(revision, url, options)
@@ skipping 390 matching lines @@
             '#Initial_checkout' ) % rev)
 
     return sha1
 
   def FullUrlForRelativeUrl(self, url):
     # Strip from last '/'
     # Equivalent to unix basename
     base_url = self.url
     return base_url[:base_url.rfind('/')] + url
 
+  def GetGitBackupDirPath(self):
+    """Returns the path where the .git folder for the current project can be
+    staged/restored. Use case: subproject moved from DEPS <-> outer project."""
+    return os.path.join(self._root_dir,
+                        'old_' + self.relpath.replace(os.sep, '_')) + '.git'
+
   def _GetMirror(self, url, options):
     """Get a git_cache.Mirror object for the argument url."""
     if not git_cache.Mirror.GetCachePath():
       return None
     mirror_kwargs = {
         'print_func': self.filter,
         'refs': []
     }
     # TODO(hinoka): This currently just fails because lkcr/lkgr are branches
     #               not tags. This also adds 20 seconds to every bot_update
@@ skipping 790 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