Add --gerrit_no_reset for who need to use FETCH_HEAD revision.

recipe_modules/bot_update/resources/bot_update.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.
 
 # TODO(hinoka): Use logging.
 
 import cStringIO
 import codecs
 import collections
@@ skipping 1112 matching lines @@
   elif blacklist:
     for item in blacklist:
       cmd.extend(['--blacklist', item])
 
   # Only try once, since subsequent failures hide the real failure.
   try:
     call(*cmd, tries=1)
   except SubprocessFailed as e:
     raise PatchFailed(e.message, e.code, e.output)
 
-def apply_gerrit_ref(gerrit_repo, gerrit_ref, root):
+def apply_gerrit_ref(gerrit_repo, gerrit_ref, root, gerrit_reset):
   gerrit_repo = gerrit_repo or 'origin'
   assert gerrit_ref
   try:
     base_rev = git('rev-parse', 'HEAD', cwd=root).strip()
     git('retry', 'fetch', gerrit_repo, gerrit_ref, cwd=root, tries=1)
     git('checkout', 'FETCH_HEAD', cwd=root)
-    git('reset', '--soft', base_rev, cwd=root)
+    if gerrit_reset:
+      git('reset', '--soft', base_rev, cwd=root)
   except SubprocessFailed as e:
     raise PatchFailed(e.message, e.code, e.output)
 
 def check_flag(flag_file):
   """Returns True if the flag file is present."""
   return os.path.isfile(flag_file)
 
 
 def delete_flag(flag_file):
   """Remove bot update flag."""
@@ skipping 137 matching lines @@
       continue
     # TODO(hinoka): Catch SVNRevisionNotFound error maybe?
     git('fetch', 'origin', cwd=deps_name)
     force_revision(deps_name, revision)
 
 
 def ensure_checkout(solutions, revisions, first_sln, target_os, target_os_only,
                     patch_root, issue, patchset, patch_url, rietveld_server,
                     gerrit_repo, gerrit_ref, revision_mapping,
                     apply_issue_email_file, apply_issue_key_file, buildspec,
-                    gyp_env, shallow, runhooks, refs, git_cache_dir):
+                    gyp_env, shallow, runhooks, refs, git_cache_dir,
+                    gerrit_reset):
   # Get a checkout of each solution, without DEPS or hooks.
   # Calling git directly because there is no way to run Gclient without
   # invoking DEPS.
   print 'Fetching Git checkout'
 
   git_ref = git_checkout(solutions, revisions, shallow, refs, git_cache_dir)
 
   patches = None
   if patch_url:
     patches = get_svn_patch(patch_url)
@@ skipping 45 matching lines @@
   ensure_deps_revisions(gclient_output.get('solutions', {}),
                         dir_names, revisions)
   # Apply the rest of the patch here (sans DEPS)
   if patches:
     apply_svn_patch(patch_root, patches, blacklist=already_patched)
   elif issue:
     apply_rietveld_issue(issue, patchset, patch_root, rietveld_server,
                          revision_mapping, git_ref, apply_issue_email_file,
                          apply_issue_key_file, blacklist=already_patched)
   elif gerrit_ref:
-    apply_gerrit_ref(gerrit_repo, gerrit_ref, patch_root)
+    apply_gerrit_ref(gerrit_repo, gerrit_ref, patch_root, gerrit_reset)
 
   # Reset the deps_file point in the solutions so that hooks get run properly.
   for sln in solutions:
     sln['deps_file'] = sln.get('deps_file', 'DEPS').replace('.DEPS.git', 'DEPS')
   gclient_configure(solutions, target_os, target_os_only, git_cache_dir)
 
   return gclient_output
 
 
 def parse_revisions(revisions, root):
@@ skipping 58 matching lines @@
   parse.add_option('--patch_url', help='Optional URL to SVN patch.')
   parse.add_option('--root', dest='patch_root',
                    help='DEPRECATED: Use --patch_root.')
   parse.add_option('--patch_root', help='Directory to patch on top of.')
   parse.add_option('--rietveld_server',
                    default='codereview.chromium.org',
                    help='Rietveld server.')
   parse.add_option('--gerrit_repo',
                    help='Gerrit repository to pull the ref from.')
   parse.add_option('--gerrit_ref', help='Gerrit ref to apply.')
+  parse.add_option('--gerrit_no_reset', action='store_true',
+                   help='Bypass calling reset after applying a gerrit ref.')
   parse.add_option('--specs', help='Gcilent spec.')
   parse.add_option('--master', help='Master name.')
   parse.add_option('-f', '--force', action='store_true',
                    help='Bypass check to see if we want to be run. '
                         'Should ONLY be used locally or by smart recipes.')
   parse.add_option('--revision_mapping',
                    help='{"path/to/repo/": "property_name"}')
   parse.add_option('--revision_mapping_file',
                    help=('Same as revision_mapping, except its a path to a json'
                          ' file containing that format.'))
@@ skipping 149 matching lines @@
           apply_issue_key_file=options.apply_issue_key_file,
 
           # For official builders.
           buildspec=buildspec,
           gyp_env=options.gyp_env,
           runhooks=not options.no_runhooks,
 
           # Finally, extra configurations such as shallowness of the clone.
           shallow=options.shallow,
           refs=options.refs,
-          git_cache_dir=options.git_cache_dir)
+          git_cache_dir=options.git_cache_dir,
+          gerrit_reset=not options.gerrit_no_reset)
       gclient_output = ensure_checkout(**checkout_parameters)
     except GclientSyncFailed:
       print 'We failed gclient sync, lets delete the checkout and retry.'
       ensure_no_checkout(dir_names, '*')
       gclient_output = ensure_checkout(**checkout_parameters)
   except PatchFailed as e:
     if options.output_json:
       # Tell recipes information such as root, got_revision, etc.
       emit_json(options.output_json,
                 did_run=True,
@@ skipping 125 matching lines @@
   except Exception:
     # Unexpected failure.
     emit_flag(options.flag_file)
     raise
   else:
     emit_flag(options.flag_file)
 
 
 if __name__ == '__main__':
   sys.exit(main())