Fix various issues in the roll_gn script.

tools/gn/bin/roll_gn.py

 # 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.
 
 """An auto-roller for GN binaries into Chromium.
 
 This script is used to update the GN binaries that a Chromium
 checkout uses. In order to update the binaries, one must follow
 four steps in order:
 
@@ skipping 164 matching lines @@
       new_deps = deps_content.replace("'buildtools_revision':",
                                       "'buildtools_revision':  ")
 
     with open('DEPS', 'w') as fp:
       fp.write(new_deps)
 
   def WaitForBuildToFinish(self):
     print('Checking build')
     results = self.CheckBuild()
     while (len(results) < 3 or
-           any(r['state'] == 'pending' for r in results.values())):
+           any(r['state'] in ('pending', 'started')
+               for r in results.values())):
       print()
       print('Sleeping for 30 seconds')
       time.sleep(30)
       print('Checking build')
       results = self.CheckBuild()
-    return 0 if all(r['state'] == 'success' for r in results.values()) else 1
+
+    ret = 0 if all(r['state'] == 'success' for r in results.values()) else 1
+    if ret:
+      print('Build failed.')
+    else:
+      print('Builds ready.')
+
+    # Close the build CL and move off of the build branch back to whatever
+    # we were on before.
+    self.Call('git-cl set-close')
+    self.MovetoLastHead()
+
+    return ret
 
   def CheckBuild(self):
     _, out, _ = self.Call('git-cl issue')
 
     issue = int(out.split()[2])
 
     _, out, _ = self.Call('git config user.email')
     email = ''
     rpc_server = upload.GetRpcServer(CODE_REVIEW_SERVER, email)
     try:
@@ skipping 55 matching lines @@
       print('  sha1:  %s' % r['sha1'])
       print('  state: %s' % r['state'])
       print('  build: %s' % r['build'])
       print('  url:   %s' % r['url'])
       print()
 
     return results
 
   def RollBuildtools(self):
     results = self.CheckBuild()
-    if not all(r['state'] == 'success' for r in results.values()):
+    if (len(results) < 3 or
+        not all(r['state'] == 'success' for r in results.values())):
       print("Roll isn't done or didn't succeed, exiting:")
       return 1
 
     desc = self.GetBuildtoolsDesc()
 
     self.Call('git new-branch roll_buildtools_gn_%s' % self.new_gn_version,
               cwd=self.buildtools_dir)
 
     for platform in results:
       fname = 'gn.exe.sha1' if platform == 'win' else 'gn.sha1'
@@ skipping 21 matching lines @@
             print(err)
         return ret
 
     # Fetch the revision we just committed so that RollDEPS will find it.
     self.Call('git fetch', cwd=self.buildtools_dir)
 
     # Reset buildtools to the new commit so that we're not still on the
     # merged branch.
     self.Call('git checkout origin/master', cwd=self.buildtools_dir)
 
+    _, out, _ = self.Call('git rev-parse origin/master',
+                          cwd=self.buildtools_dir)
+    new_buildtools_commitish = out.strip()
+    print('Ready to roll buildtools to %s in DEPS' % new_buildtools_commitish)
+
     return 0
 
   def RollDEPS(self):
     ret, _, _ = self.Call('git new-branch roll_gn_%s' % self.new_gn_version)
     if ret:
       print('Failed to create a new branch for roll_gn_%s' %
             self.new_gn_version)
       return 1
 
     _, out, _ = self.Call('git rev-parse origin/master',
@@ skipping 10 matching lines @@
           new_deps_lines.append("  'buildtools_revision': '%s',\n" %
                                 new_buildtools_commitish)
         else:
           new_deps_lines.append(l)
 
     if not old_buildtools_commitish:
       print('Could not update DEPS properly, exiting')
       return 1
 
     with open('DEPS', 'w') as fp:
-      fp.write(''.join(new_deps_lines) + '\n')
+      fp.write(''.join(new_deps_lines))
 
     desc = self.GetDEPSRollDesc(old_buildtools_commitish,
                                 new_buildtools_commitish)
     desc_file = tempfile.NamedTemporaryFile(delete=False)
     try:
       desc_file.write(desc)
       desc_file.close()
       self.Call('git commit -a -F %s' % desc_file.name)
       self.Call('git-cl upload -f --send-mail --use-commit-queue')
     finally:
       os.remove(desc_file.name)
 
-    # Intentionally leave the src checkout on the new branch with the roll
-    # since we're not auto-committing it.
+    # Move off of the roll branch onto whatever we were on before.
+    # Do not explicitly close the roll CL issue, however; the CQ
+    # will close it when the roll lands, assuming it does so.
+    self.MoveToLastHead()
 
     return 0
 
+  def MovetoLastHead(self):
+    _, out, _ = self.Call('git reflog -1')
+    m = re.match('moving from ([^\s]+)', out)
+    last_head = m.group(1)
+    self.Call('git checkout %s' % last_head)
+
   def GetBuildtoolsDesc(self):
     gn_changes = self.GetGNChanges()
     return (
       'Roll gn %s..%s (r%s:r%s)\n'
       '\n'
       '%s'
       '\n'
       'TBR=%s\n' % (
         self.old_gn_commitish[:COMMITISH_DIGITS],
         self.new_gn_commitish[:COMMITISH_DIGITS],
         self.old_gn_version,
         self.new_gn_version,
         gn_changes,
         self.reviewer,
       ))
 
   def GetDEPSRollDesc(self, old_buildtools_commitish, new_buildtools_commitish):
     gn_changes = self.GetGNChanges()
 
     return (
       'Roll buildtools %s..%s\n'
       '\n'
       '  In order to roll GN %s..%s (r%s:r%s) and pick up\n'
       '  the following changes:\n'
       '\n'
       '%s'
       '\n'
       'TBR=%s\n'
-      'CQ_EXTRA_TRYBOTS=tryserver.chromium.mac:mac_chromium_gn_rel,'
-      'mac_chromium_gn_dbg;'
+      'CQ_EXTRA_TRYBOTS=tryserver.chromium.mac:mac_chromium_gn_dbg;'
       'tryserver.chromium.win:win8_chromium_gn_dbg,'
       'win_chromium_gn_x64_rel\n' % (
         old_buildtools_commitish[:COMMITISH_DIGITS],
         new_buildtools_commitish[:COMMITISH_DIGITS],
         self.old_gn_commitish[:COMMITISH_DIGITS],
         self.new_gn_commitish[:COMMITISH_DIGITS],
         self.old_gn_version,
         self.new_gn_version,
         gn_changes,
         self.reviewer,
       ))
 
   def GetGNChanges(self):
     _, out, _ = self.Call(
         "git log --pretty='  %h %s' " +
         "%s..%s tools/gn" % (self.old_gn_commitish, self.new_gn_commitish))
     return out
 
   def Call(self, cmd, cwd=None):
     proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, shell=True,
                             cwd=(cwd or self.chromium_src_dir))
     out, err = proc.communicate()
     return proc.returncode, out, err
 
 
 if __name__ == '__main__':
   roller = GNRoller()
   sys.exit(roller.Roll())