Reset to correct version when switching upstream repository for a git dependency.

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."""
 
 import logging
 import os
 import posixpath
 import re
@@ skipping 296 matching lines @@
     if current_url != url and url != 'git://foo':
       print('_____ switching %s to a new upstream' % self.relpath)
       # Make sure it's clean
       self._CheckClean(rev_str)
       # Switch over to the new upstream
       self._Run(['remote', 'set-url', 'origin', url], options)
       quiet = []
       if not options.verbose:
         quiet = ['--quiet']
       self._Run(['fetch', 'origin', '--prune'] + quiet, options)
-      self._Run(['reset', '--hard', 'origin/master'] + quiet, options)
+      self._Run(['reset', '--hard', revision] + quiet, options)
       self.UpdateSubmoduleConfig()
       files = self._Capture(['ls-files']).splitlines()
       file_list.extend([os.path.join(self.checkout_path, f) for f in files])
       return
 
     cur_branch = self._GetCurrentBranch()
 
     # Cases:
     # 0) HEAD is detached. Probably from our initial clone.
     #   - make sure HEAD is contained by a named ref, then update.
@@ skipping 887 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