Allow gclient sync to overwrite untracked files when moving detached git HEAD.

Allow gclient sync to overwrite untracked files when moving detached git HEAD.

Do it only when both --force and --delete_unversioned_trees are specified.

BUG=386878
R=iannucci@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=278770

[Vadim Sh., 2014-06-20 06:46:46]

PTAL

Disclaimer: code paths in gclient_scm.py look alient to me. Also I only verified
that 'git --force checkout <hash>' does overwrite untracked file, but I'm not
sure what other side effects it can have.

My hope that poor chrome devs do not run theirs gclient's with --force
--delete_unversioned_trees all the time. Because if they do, this CL introduces
a new avenue for data loss. But I think 'delete_unversioned' implies that
already.

https://codereview.chromium.org/334633004/diff/1/gclient_scm.py
File gclient_scm.py (right):

https://codereview.chromium.org/334633004/diff/1/gclient_scm.py#newcode491
gclient_scm.py:491: if options.force and options.delete_unversioned_trees:
The more natural combination would be "--force --reset", but 'gclient sync' step
on bots is not using --reset, and enabling --reset there would make it a lot
slower (I think). So I choose less natural combination of '--force
--delete_unversioned_trees' that's already passed by gclient sync step.

In some sense force git checkout does delete unversioned trees... sort of.

[Vadim Sh., 2014-06-20 06:53:09]

Oh, another datapoint: when syncing to SVN-based solution with exact same flags,
SVN just silently overwrites the file (I think). At least gclient sync isn't
failing.

Log's here:
http://build.chromium.org/p/chromium.win/builders/Win%20Builder/builds/526/st...
________ running 'svn update c:\b\build\slave\Win_Builder\build\src --revision
278281 --force --accept theirs-conflict --ignore-externals' in
'c:\b\build\slave\Win_Builder\build'
U   
C:\b\build\slave\Win_Builder\build\src\build\android\pylib\perf\test_runner.py
U    C:\b\build\slave\Win_Builder\build\src\build\android\pylib\perf\setup.py
U   
C:\b\build\slave\Win_Builder\build\src\ppapi\examples\video_decode\video_decode.cc
U    C:\b\build\slave\Win_Builder\build\src\chrome\tools\build\repack_locales.py
U    C:\b\build\slave\Win_Builder\build\src\chrome\app\OWNERS
E   
C:\b\build\slave\Win_Builder\build\src\chrome\app\address_input_strings.grdp
U   
C:\b\build\slave\Win_Builder\build\src\third_party\libaddressinput\chromium\tools\update-strings.py
U   
C:\b\build\slave\Win_Builder\build\src\third_party\libaddressinput\libaddressinput.gyp
Updated to revision 278281.

Notice what happened to address_input_strings.grdp.

[szager1, 2014-06-20 18:12:06]

lgtm

[Vadim Sh., 2014-06-20 18:12:32]

The CQ bit was checked by vadimsh@chromium.org

[commit-bot: I haz the power, 2014-06-20 18:13:13]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/vadimsh@chromium.org/334633004/1

[commit-bot: I haz the power, 2014-06-20 18:15:39]

Change committed as 278770