Add a --squash option to Gerrit uploads.

Add a --squash option to Gerrit uploads.

This makes uploading to Gerrit with `git cl` more similar to uploading to Rietveld, by uploading a squashed commit containing the diff to the newest common ancestor.

Uploaded commits are stored in refs/heads/git_cl_uploads/<branch> (and their commit message is used for the squash commit), which allows amending the commit message to change it on the uploaded CL, and looking through the reflog to find old uploaded versions.

BUG=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=294077

[Bernhard Bauer, 2015-02-13 14:52:33]

bauerb@chromium.org changed reviewers:
+ maruel@chromium.org, zty@chromium.org

[Bernhard Bauer, 2015-02-13 14:52:33]

Please review!

[M-A Ruel, 2015-02-13 16:19:27]

https://codereview.chromium.org/200023004/diff/50001/git_cl.py
File git_cl.py (right):

https://codereview.chromium.org/200023004/diff/50001/git_cl.py#newcode115
git_cl.py:115: 
2 lines

https://codereview.chromium.org/200023004/diff/50001/git_cl.py#newcode117
git_cl.py:117: """Returns stdout, supresses stderr and ignores the return
code."""
suppresses

https://codereview.chromium.org/200023004/diff/50001/git_cl.py#newcode1666
git_cl.py:1666: file_handle, msg_file = tempfile.mkstemp(text=True,
prefix='commit_msg')
You have to os.close() it otherwise it'll fail on Windows. Use a try/finally.

[Bernhard Bauer, 2015-02-13 17:08:11]

Thanks for the review!

https://codereview.chromium.org/200023004/diff/50001/git_cl.py
File git_cl.py (right):

https://codereview.chromium.org/200023004/diff/50001/git_cl.py#newcode115
git_cl.py:115: 
On 2015/02/13 16:19:27, M-A Ruel wrote:
> 2 lines

Done.

https://codereview.chromium.org/200023004/diff/50001/git_cl.py#newcode117
git_cl.py:117: """Returns stdout, supresses stderr and ignores the return
code."""
On 2015/02/13 16:19:27, M-A Ruel wrote:
> suppresses

Done.

https://codereview.chromium.org/200023004/diff/50001/git_cl.py#newcode1666
git_cl.py:1666: file_handle, msg_file = tempfile.mkstemp(text=True,
prefix='commit_msg')
On 2015/02/13 16:19:27, M-A Ruel wrote:
> You have to os.close() it otherwise it'll fail on Windows. Use a try/finally.

Done.

[Marc-Antoine Ruel (Google), 2015-02-13 17:32:12]

maruel@google.com changed reviewers:
+ maruel@google.com

[Marc-Antoine Ruel (Google), 2015-02-13 17:32:13]

https://codereview.chromium.org/200023004/diff/70001/git_cl.py
File git_cl.py (right):

https://codereview.chromium.org/200023004/diff/70001/git_cl.py#newcode1678
git_cl.py:1678: os.close(file_handle)
You need to close the handle before calling the command so right after line
1671.

[Bernhard Bauer, 2015-02-13 18:51:48]

https://codereview.chromium.org/200023004/diff/70001/git_cl.py
File git_cl.py (right):

https://codereview.chromium.org/200023004/diff/70001/git_cl.py#newcode1678
git_cl.py:1678: os.close(file_handle)
On 2015/02/13 17:32:13, Marc-Antoine Ruel (Google) wrote:
> You need to close the handle before calling the command so right after line
> 1671.

Oh, duh. Done.

[M-A Ruel, 2015-02-13 18:53:55]

https://codereview.chromium.org/200023004/diff/90001/git_cl.py
File git_cl.py (right):

https://codereview.chromium.org/200023004/diff/90001/git_cl.py#newcode1675
git_cl.py:1675: os.close(file_handle)
No, really after 1671, as on Windows, the handle will not have SHARED_* access
flags, which causes the RunCommand() to fail.

[Bernhard Bauer, 2015-02-13 19:00:52]

https://codereview.chromium.org/200023004/diff/90001/git_cl.py
File git_cl.py (right):

https://codereview.chromium.org/200023004/diff/90001/git_cl.py#newcode1675
git_cl.py:1675: os.close(file_handle)
On 2015/02/13 18:53:55, M-A Ruel wrote:
> No, really after 1671, as on Windows, the handle will not have SHARED_* access
> flags, which causes the RunCommand() to fail.

Oh, I see; I thought the problem was the remove(). Thanks for the explanation!

[M-A Ruel, 2015-02-13 19:03:51]

lgtm

https://codereview.chromium.org/200023004/diff/110001/git_cl.py
File git_cl.py (right):

https://codereview.chromium.org/200023004/diff/110001/git_cl.py#newcode1667
git_cl.py:1667: file_handle, msg_file = tempfile.mkstemp(text=True,
BTW, I never used text=True and it never has been useful in any way.

[Bernhard Bauer, 2015-02-16 10:42:18]

The CQ bit was checked by bauerb@chromium.org

[commit-bot: I haz the power, 2015-02-16 10:42:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/200023004/110001

[commit-bot: I haz the power, 2015-02-16 10:45:41]

Committed patchset #6 (id:110001) as
http://src.chromium.org/viewvc/chrome?view=rev&revision=294077