Allow target_ref to be modified by subsequent patchsets with logging

Allow target_ref to be modified by subsequent patchsets with logging

The motivation of this CL are changes that are created by tracking "refs/pending/heads/lkcr".
Eg: https://codereview.chromium.org/812793002
A possible workflow would be to run "git reparent-branch origin/master" or "git branch --set-upstream-to origin/master" on such CLs and reupload when ready to commit.

BUG=435702
NOTRY=true
TBR=jrobbins

Committed: https://chromium.googlesource.com/infra/infra/+/77f74e78d63a53f561f21f8854856fbe5c956723

[rmistry, 2014-12-18 18:00:59]

rmistry@google.com changed reviewers:
+ agable@chromium.org, jrobbins@chromium.org

[Jason Robbins -- corp, 2014-12-18 18:59:55]

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

[Jason Robbins -- corp, 2014-12-18 18:59:55]

lgtm

[rmistry, 2014-12-18 19:03:44]

Thanks Jason.
Aaron what do you think of this idea?

[rmistry, 2014-12-18 21:40:42]

Hi Aaron, I am going to submit this because of complains of a lack of
workaround. We can discuss a better solution after we have this in place.

[rmistry, 2014-12-18 21:41:06]

The CQ bit was checked by rmistry@google.com

[commit-bot: I haz the power, 2014-12-18 21:41:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/806373005/40001

[commit-bot: I haz the power, 2014-12-18 21:41:53]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-12-18 21:41:53]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[rmistry, 2014-12-18 21:42:56]

The CQ bit was checked by rmistry@google.com

[commit-bot: I haz the power, 2014-12-18 21:43:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/806373005/40001

[jrobbins, 2014-12-18 21:44:38]

lgtm from my correct account.

[rmistry, 2014-12-18 21:45:59]

The CQ bit was unchecked by rmistry@google.com

[rmistry, 2014-12-18 21:46:03]

The CQ bit was checked by rmistry@google.com

[commit-bot: I haz the power, 2014-12-18 21:46:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/806373005/40001

[commit-bot: I haz the power, 2014-12-18 21:46:13]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-12-18 21:46:14]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[rmistry, 2014-12-18 21:47:20]

The CQ bit was checked by rmistry@google.com

[commit-bot: I haz the power, 2014-12-18 21:47:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/806373005/40001

[commit-bot: I haz the power, 2014-12-18 21:48:13]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/infra/infra/+/77f74e78d63a53f561f21f8854856...

[agable, 2014-12-19 17:52:57]

Being able to modify the target ref on subsequent uploads LGTM. We do need to be
careful about interactions between this and the CQ accepting previously-run
tryjobs. We need to make sure it isn't possible to upload a patch against
refs/foo, try it, change it to refs/bar, and commit it using the previous try
successes to bypass the CQ.

https://codereview.chromium.org/806373005/diff/40001/appengine/chromium_rietv...
File appengine/chromium_rietveld/codereview/views.py (right):

https://codereview.chromium.org/806373005/diff/40001/appengine/chromium_rietv...
appengine/chromium_rietveld/codereview/views.py:1349: logging.warn('Issue %d for
%s did not start with refs/pending/',
nit: "Target ref %s for issue %d in project %s did not start..."