Fix a case branch...rietveldissue is None.

Fix a case branch...rietveldissue is None.

BUG=None
NOTRY=true


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=192050

[Dai Mikurube (NOT FULLTIME), 2013-04-03 06:49:52]

Hi koz and maruel,

I found that your http://crrev.com/191895 can fail when git's
branch...rietveldissue is empty.  I have no idea when it happens, but I actually
couldn't upload my patch for this case with the following message:

dmikurube@work:~/work/chromium/src>git cl upload HEAD^
Using 50% similarity for rename/copy detection. Override with --similarity.
Loaded authentication cookies from .../home/dmikurube/.codereview_upload_cookies
Running presubmit upload checks ...

Running pylint on 8 files.

Presubmit checks took 3.3s to calculate.

Presubmit checks passed.
Traceback (most recent call last):
  File ".../home/dmikurube/depot_tools/git_cl.py", line 1912, in <module>
    sys.exit(main(sys.argv[1:]))
  File ".../home/dmikurube/depot_tools/git_cl.py", line 1897, in main
    return command(parser, argv[1:])
  File ".../home/dmikurube/depot_tools/git_cl.py", line 1301, in CMDupload
    % (local_patchset, latest_patchset))
TypeError: %d format: a number is required, not NoneType
Sending crash report ...
  args: ['.../home/dmikurube/depot_tools/git_cl.py', 'upload', 'HEAD^']
  cwd: .../home/dmikurube/work/chromium/src
  exception: %d format: a number is required, not NoneType
  host: ume.tok.corp.google.com
  stack:   File ".../home/dmikurube/depot_too
  user: dmikurube
  version: 2.7.3 (default, Aug  1 2012, 05:14:39) 
[GCC 4.6.3
A stack trace has been sent to the maintainers.

[Marc-Antoine Ruel (Google), 2013-04-03 11:37:53]

lgtm

[commit-bot: I haz the power, 2013-04-03 11:38:02]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dmikurube@chromium.org/13513002/1

[commit-bot: I haz the power, 2013-04-03 11:40:24]

Change committed as 192050