Further shorten the lastchange string.

Further shorten the lastchange string.

Even the 40-character hash causes problems when the pieces of the string before
it push the length to >64 characters. Truncating it is a temporary fix until
we discuss ways to accept strings longer than 64 chars.

R=cmp@chromium.org, scottmg@chromium.org
NOTRY=True
BUG=406783
Committed: https://crrev.com/15a2a65986f6dec827cce5bc7d58601ed9b1eb2a
Cr-Commit-Position: refs/heads/master@{#291626}

[cmp, 2014-08-24 18:39:54]

lgtm

[agable, 2014-08-24 18:40:28]

The CQ bit was checked by agable@chromium.org

[commit-bot: I haz the power, 2014-08-24 18:40:43]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/agable@chromium.org/499133003/20001

[commit-bot: I haz the power, 2014-08-24 18:41:17]

Committed patchset #2 (20001) as f292d1c2781fd2e4b9d0eaab79cddd908f548d21

[commit-bot: I haz the power, 2014-09-10 02:32:36]

Patchset 2 (id:??) landed as
https://crrev.com/15a2a65986f6dec827cce5bc7d58601ed9b1eb2a
Cr-Commit-Position: refs/heads/master@{#291626}