Add --upstream option to gclient to scrape git checkouts back to upstream state.

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 244 matching lines @@
     All updated files will be appended to file_list.
 
     Raises:
       Error: if can't get URL for relative path.
     """
     if args:
       raise gclient_utils.Error("Unsupported argument(s): %s" % ",".join(args))
 
     self._CheckMinVersion("1.6.6")
 
-    default_rev = "refs/heads/master"
+    if not options.nuclear:
+      default_rev = "refs/heads/master"
+    else:
+      default_rev = "refs/remotes/origin/master"

[Dirk Pranke, 2013/06/27 19:57:52]

It seems like refs/heads/master can't be the right default rev in any case. I
also don't like using hard-coded branch names, period. Perhaps this should be
'{u}' (in both cases) ? 

Lastly, I would flip the order of the two branches so that you don't also need a
'not', if you end up w/ two branches.

     url, deps_revision = gclient_utils.SplitUrlRevision(self.url)
     rev_str = ""
     revision = deps_revision
     managed = True
     if options.revision:
       # Override the revision number.
       revision = str(options.revision)
     if revision == 'unmanaged':
       revision = None
       managed = False
     if not revision:
       revision = default_rev
 
+    if revision == 'HEAD' and options.nuclear:
+      revision = 'refs/remotes/origin/master'

[Dirk Pranke, 2013/06/27 19:57:52]

This doesn't seem right. In what situation do we say -r HEAD explicitly ? 

I would be more inclined to either leave -r HEAD alone or err out saying that -r
and --nuclear are incompatible, but maybe neither of those are acceptable?

[iannucci, 2013/06/27 22:56:51]

If we have deps e.g. third_party/WebKit@HEAD

+
     if gclient_utils.IsDateRevision(revision):
       # Date-revisions only work on git-repositories if the reflog hasn't
       # expired yet. Use rev-list to get the corresponding revision.
       #  git rev-list -n 1 --before='time-stamp' branchname
       if options.transitive:
         print('Warning: --transitive only works for SVN repositories.')
         revision = default_rev
 
     rev_str = ' at %s' % revision
     files = []
@@ skipping 134 matching lines @@
             continue
           raise
 
       if verbose:
         print(remote_output.strip())
 
       self._UpdateBranchHeads(options, fetch=True)
 
     # This is a big hammer, debatable if it should even be here...
     if options.force or options.reset:
-      self._Run(['reset', '--hard', 'HEAD'], options)
+      target = 'refs/remotes/origin/master' if options.nuclear else 'HEAD'

[Dirk Pranke, 2013/06/27 19:57:52]

Same sorts of comments as above, plus it's not clear to me that this shouldn't
just be a part of the UpstreamBranch() logic above on 401-409.

+      self._Run(['reset', '--hard', target], options)
 
     if current_type == 'detached':
       # case 0
       self._CheckClean(rev_str)
       self._CheckDetachedHead(rev_str, options)
       self._Capture(['checkout', '--quiet', '%s' % revision])
       if not printed_path:
         print('\n_____ %s%s' % (self.relpath, rev_str))
     elif current_type == 'hash':
       # case 1
@@ skipping 126 matching lines @@
 
     All reverted files will be appended to file_list.
     """
     if not os.path.isdir(self.checkout_path):
       # revert won't work if the directory doesn't exist. It needs to
       # checkout instead.
       print('\n_____ %s is missing, synching instead' % self.relpath)
       # Don't reuse the args.
       return self.update(options, [], file_list)
 
-    default_rev = "refs/heads/master"
+    if options.nuclear:
+      default_rev = "refs/remotes/origin/master"
+    else:
+      default_rev = "refs/heads/master"
     _, deps_revision = gclient_utils.SplitUrlRevision(self.url)
     if not deps_revision:
       deps_revision = default_rev
     if deps_revision.startswith('refs/heads/'):
       deps_revision = deps_revision.replace('refs/heads/', 'origin/')
 
     files = self._Capture(['diff', deps_revision, '--name-only']).split()
     self._Run(['reset', '--hard', deps_revision], options)
     self._Run(['clean', '-f', '-d'], options)
     file_list.extend([os.path.join(self.checkout_path, f) for f in files])
@@ skipping 738 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