Extend the git-cl-comments command functionality

Extend the git-cl-comments command functionality

The "comments" command is taught to:
- accept an arbitrary review issue id;
- post comments on the current or specified review issue.

This is required for the auto-rebaseline bot to notify a
rebaseline requestor of the fact that the rebaseline has happened
by means of posting a comment to the review issue that requested
the rebaseline, as suggested by iannucci@.

R=iannucci, szager, dpranke

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=292844

[apavlov, 2014-10-31 13:31:06]

apavlov@chromium.org changed reviewers:
+ dpranke@google.com

[apavlov, 2014-10-31 13:31:12]

PTAL

[iannucci, 2014-10-31 23:27:31]

lgtm

[iannucci, 2014-10-31 23:29:12]

oop, one comment. I think this breaks the default issue flow.

https://codereview.chromium.org/693873002/diff/1/git_cl.py
File git_cl.py (right):

https://codereview.chromium.org/693873002/diff/1/git_cl.py#newcode1446
git_cl.py:1446: help="review issue id (defaults to current issue)")
I think this should actually default to cl.GetIssue().

[apavlov, 2014-11-01 06:59:21]

https://codereview.chromium.org/693873002/diff/1/git_cl.py
File git_cl.py (right):

https://codereview.chromium.org/693873002/diff/1/git_cl.py#newcode1446
git_cl.py:1446: help="review issue id (defaults to current issue)")
On 2014/10/31 23:29:12, iannucci wrote:
> I think this should actually default to cl.GetIssue().

Actually, that's what I meant. What is the right word to express this (rather
than "current")?

[apavlov, 2014-11-01 20:06:22]

https://codereview.chromium.org/693873002/diff/1/git_cl.py
File git_cl.py (right):

https://codereview.chromium.org/693873002/diff/1/git_cl.py#newcode1456
git_cl.py:1456: cl = Changelist(issue=issue)
If -i is not specified, the default value of None is passed into the Changelist
ctor, so the behavior is intact in this case.

[apavlov, 2014-11-05 09:03:18]

The CQ bit was checked by apavlov@chromium.org

[commit-bot: I haz the power, 2014-11-05 09:03:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/693873002/1

[commit-bot: I haz the power, 2014-11-05 09:05:31]

Committed patchset #1 (id:1) as 292844