Fix git branch parsing.

git_common.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.
 
 # Monkeypatch IMapIterator so that Ctrl-C can kill everything properly.
 # Derived from https://gist.github.com/aljungberg/626518
 import multiprocessing.pool
 from multiprocessing.pool import IMapIterator
 def wrapper(func):
   def wrap(self, timeout=None):
@@ skipping 275 matching lines @@
   """Return {branch: <|option| value>} for all branches."""
   try:
     reg = re.compile(r'^branch\.(.*)\.%s$' % option)
     lines = run('config', '--get-regexp', reg.pattern).splitlines()
     return {reg.match(k).group(1): v for k, v in (l.split() for l in lines)}
   except subprocess2.CalledProcessError:
     return {}
 
 
 def branches(*args):
-  NO_BRANCH = ('* (no branch', '* (detached from ')
+  NO_BRANCH = ('* (no branch', '* (detached', '* (HEAD detached')
 
   key = 'depot-tools.branch-limit'
   limit = 20
   try:
     limit = int(config(key, limit))
   except ValueError:
     pass
 
   raw_branches = run('branch', *args).splitlines()
 
@@ skipping 480 matching lines @@
         hash=branch_hash, upstream=upstream_branch, ahead=ahead, behind=behind)
 
   # Set None for upstreams which are not branches (e.g empty upstream, remotes
   # and deleted upstream branches).
   missing_upstreams = {}
   for info in info_map.values():
     if info.upstream not in info_map and info.upstream not in missing_upstreams:
       missing_upstreams[info.upstream] = None
 
   return dict(info_map.items() + missing_upstreams.items())