Report a 12-digit abbreviated hash in the "committed" message

Report the entire hash in the "committed" message.

This concerns the "committed" message posted to Rietveld. Prior to
34504a15bb3e, this used the committer's own core.abbrev. Now it's using
a hard-coded 7. Per recent discussions on chromium-dev, 7 is
insufficient to uniquely identify commits in large repositories such as
ours. If any abbreviation is to be done, a 12-digit minimum should be
used, but there's no reason not to use the entire hash.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=292164

[Mark Mentovai, 2014-09-23 02:41:19]

mark@chromium.org changed reviewers:
+ iannucci@chromium.org

[Mark Mentovai, 2014-09-25 22:34:50]

Ping.

[iannucci, 2014-09-25 23:50:27]

On 2014/09/25 22:34:50, Mark Mentovai wrote:
> Ping.

lgtm, though to be honest, I think the abbreviated hash is wrong anyway, and it
should be the full hash. Over time 12 (or 13 or 14) will eventually collide
somewhere (yay birthday paradox), causing old data to suddenly become
ambiguous... wdyt about just making it the full hash?

[Mark Mentovai, 2014-09-26 00:48:38]

OK, updated to use the entire hash.

[Mark Mentovai, 2014-09-26 00:49:04]

I agree, for what it’s worth. I don’t think our tools should actually abbreviate
anywhere.

[iannucci, 2014-09-26 00:52:34]

lgtm

[iannucci, 2014-09-26 00:52:47]

On 2014/09/26 00:52:34, iannucci wrote:
> lgtm

Oh, though you should probably update the description.

[Mark Mentovai, 2014-09-26 01:04:05]

I thought I did.

I left the “subject” alone to not break it into a new e-mail thread, but that
doesn’t make it into the commit log. Is the description OK now?

[iannucci, 2014-09-26 08:28:52]

lgtm

[Mark Mentovai, 2014-09-26 21:45:23]

The CQ bit was checked by mark@chromium.org

[commit-bot: I haz the power, 2014-09-26 21:45:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/592293002/20001

[commit-bot: I haz the power, 2014-09-26 21:48:20]

Committed patchset #2 (id:20001) as 292164