Add GetRemoteMasterHash() function to git_utils.py.

Add GetRemoteMasterHash() function to git_utils.py.

This should fix borenet's TODO.

BUG=None
TEST=None
R=borenet@google.com

Committed: https://skia.googlesource.com/buildbot/+/49a080701357dc50ec03f40ccd9a2c64873f68af

[tfarina, 2014-06-05 04:30:43]

Is this OK?

If yes, I can migrate the other uses of ls-remote [1] to it in a follow up CL
(or in this CL if you prefer).

[1] - chrome_canary_update.py, update.py, sync_skia_in_chrome.py

[borenet, 2014-06-05 14:17:31]

On 2014/06/05 04:30:43, tfarina wrote:
> Is this OK?
> 
> If yes, I can migrate the other uses of ls-remote [1] to it in a follow up CL
> (or in this CL if you prefer).
> 
> [1] - chrome_canary_update.py, update.py, sync_skia_in_chrome.py

LGTM.  You can change the other uses in this CL or in another, I have no
preference.

[tfarina, 2014-06-05 18:30:20]

The CQ bit was checked by tfarina@chromium.org

[commit-bot: I haz the power, 2014-06-05 18:30:59]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/tfarina@chromium.org/315083006/1

[commit-bot: I haz the power, 2014-06-05 18:31:05]

Change committed as 49a080701357dc50ec03f40ccd9a2c64873f68af