Make marked merge base invalid when the upstream changes.

git_reparent_branch.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 """Change the upstream of the current branch."""
 
 import argparse
 import sys
 
 import subprocess2
 
 from git_common import upstream, current_branch, run, tags, set_branch_config
-from git_common import get_or_create_merge_base, root
+from git_common import get_or_create_merge_base, root, manual_merge_base
 
 import git_rebase_update
 
 def main(args):
   root_ref = root()
 
   parser = argparse.ArgumentParser()
   g = parser.add_mutually_exclusive_group()
   g.add_argument('new_parent', nargs='?',
                  help='New parent branch (or tag) to reparent to.')
@@ skipping 12 matching lines @@
     new_parent = 'lkgr'
   else:
     new_parent = opts.new_parent
   cur_parent = upstream(branch)
 
   if branch == 'HEAD' or not branch:
     parser.error('Must be on the branch you want to reparent')
   if new_parent == cur_parent:
     parser.error('Cannot reparent a branch to its existing parent')
 
-  get_or_create_merge_base(branch, cur_parent)
+  mbase = get_or_create_merge_base(branch, cur_parent)
 
   all_tags = tags()
   if cur_parent in all_tags:
     cur_parent += ' [tag]'
 
   try:
     run('show-ref', new_parent)
   except subprocess2.CalledProcessError:
     print >> sys.stderr, 'fatal: invalid reference: %s' % new_parent
     return 1
 
   if new_parent in all_tags:
     print ("Reparenting %s to track %s [tag] (was %s)"
            % (branch, new_parent, cur_parent))
     set_branch_config(branch, 'remote', '.')
     set_branch_config(branch, 'merge', new_parent)
   else:
     print ("Reparenting %s to track %s (was %s)"
            % (branch, new_parent, cur_parent))
     run('branch', '--set-upstream-to', new_parent, branch)
 
+  manual_merge_base(branch, mbase, new_parent)

[iannucci, 2014/05/15 22:20:17]

this sets the same base for the branch given the new parent branch.

+
   # TODO(iannucci): ONLY rebase-update the branch which moved (and dependants)
   return git_rebase_update.main(['--no_fetch'])
 
 
 if __name__ == '__main__':  # pragma: no cover
   sys.exit(main(sys.argv[1:]))