Make correction to grep pattern to grab git hash for given commit position.

Make correction to grep pattern to grab git hash for given commit position.

Note that the pattern used to check commit position appears two times in reverted
CL, therefore match the pattern at begining of the line

BUG=413365, 412054
NOTRY=true

Committed: https://crrev.com/657e7fb46a5eff1680d2b079dcaebfea4e4c19a4
Cr-Commit-Position: refs/heads/master@{#294463}

[prasadv, 2014-09-11 19:50:14]

prasadv@chromium.org changed reviewers:
+ qyearsley@chromium.org, tonyg@chromium.org

[qyearsley, 2014-09-11 20:32:54]

lgtm

[prasadv, 2014-09-11 20:34:56]

The CQ bit was checked by prasadv@chromium.org

[commit-bot: I haz the power, 2014-09-11 20:39:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/564873003/1

[commit-bot: I haz the power, 2014-09-11 20:58:22]

Committed patchset #1 (id:1) as 7178ccdf3e7bdf2a24df396cdfe8bc63f7bd180a

[commit-bot: I haz the power, 2014-09-11 21:22:47]

Patchset 1 (id:??) landed as
https://crrev.com/657e7fb46a5eff1680d2b079dcaebfea4e4c19a4
Cr-Commit-Position: refs/heads/master@{#294463}