Add new tool, git find-releases

Add new tool, git find-releases

Finds the release(s) for a given change.

Relies on using "git cherry-pick -x" per
http://commondatastorage.googleapis.com/chrome-infra-docs/flat/depot_tools/docs/html/git-drover.html
so that the merge commit message contains the original commit.

Example:

d:\src\cr3\src>git show -s 53cc88da9a258bc4a34c4bff50025ee044c2e64d
commit 53cc88da9a258bc4a34c4bff50025ee044c2e64d
Author: grt <grt@chromium.org>;
Date:   Tue Jun 2 10:33:09 2015 -0700

    Beacons for tracking default browser status.

    BUG=488247
R=gab@chromium.org,wfh@chromium.org

    Review URL: https://codereview.chromium.org/1146843003

    Cr-Commit-Position: refs/heads/master@{#332423}


"Now, where did that ship?"


d:\src\cr3\src>git find-releases 53cc88da9a258bc4a34c4bff50025ee044c2e64d
commit 53cc88da9a258bc4a34c4bff50025ee044c2e64d was:
  initially in 45.0.2421.0
  merged to 43.0.2357.126 (as 8a5ccc0e0ad6b2237b2fcfffcb0ab24fe97bc77b)
  merged to 44.0.2403.39 (as d5d165943a88e51a64fd9e2fbcc781e4aaee270f)

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=296604

[Primiano Tucci (use gerrit), 2015-09-05 12:37:36]

See my internal comment, if you assume that cherry-picks are cherry-picked with
-x, you can find cherry-picks by just letting git grep for the "cherrypicked
from" line using ":/regex"

Or alternatively, if you want to be very pedantic, you could list the most
recent releases from http://omahaproxy.appspot.com/history and search for
cherrypicks only in those (there is a similar syntax to :/ which limits the
search to a given ref)

Real example: commit b6eeb74b934bb7 was taken in the m47 branch, but was also
cherry-picked on m46.
You can find it whether was cherry-picked by asking git:
$ git name-rev --name-only --tags :/"$\s\(cherry picked from commit b6eeb74b93"
46.0.2490.9~2

[scottmg, 2015-09-08 18:58:06]

scottmg@chromium.org changed reviewers:
+ primiano@chromium.org

[scottmg, 2015-09-08 18:58:59]

Thanks Primiano. I couldn't get :/"X" to work as I wanted, but grepping works
much better than patch-id anyway. PTAL at the latest version to see if you think
it's reasonable.

[Primiano Tucci (use gerrit), 2015-09-08 19:27:28]

Not an owner but LGTM.

I eventually tried to figure out what is the coding style (def UpperCase vs def
lower_with_under) for depot_tools but gave up. there doesn't seem to be any
consistency even within single python files ¯\(°_o)/¯

https://codereview.chromium.org/1332473003/diff/60001/git_find_releases.py
File git_find_releases.py (right):

https://codereview.chromium.org/1332473003/diff/60001/git_find_releases.py#ne...
git_find_releases.py:21: def NameForCommit(sha1):
Nit: GetNameForCommit (same below)

https://codereview.chromium.org/1332473003/diff/60001/git_find_releases.py#ne...
git_find_releases.py:54: except KeyboardInterrupt:
Thanks for the civilization and not bailing out with a stack trace on ctrl-c :)

[scottmg, 2015-09-08 21:21:06]

scottmg@chromium.org changed reviewers:
+ dpranke@chromium.org

[scottmg, 2015-09-08 21:21:07]

Thanks, done. Also checked for invalid commit being provided.

+dpranke for owners review

https://codereview.chromium.org/1332473003/diff/60001/git_find_releases.py
File git_find_releases.py (right):

https://codereview.chromium.org/1332473003/diff/60001/git_find_releases.py#ne...
git_find_releases.py:21: def NameForCommit(sha1):
On 2015/09/08 19:27:27, Primiano Tucci wrote:
> Nit: GetNameForCommit (same below)

Done.

[Dirk Pranke, 2015-09-08 21:36:49]

lgtm

[scottmg, 2015-09-08 21:43:56]

The CQ bit was checked by scottmg@chromium.org

[scottmg, 2015-09-08 21:43:57]

The patchset sent to the CQ was uploaded after l-g-t-m from
primiano@chromium.org
Link to the patchset: https://codereview.chromium.org/1332473003/#ps80001
(title: "nit")

[commit-bot: I haz the power, 2015-09-08 21:44:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1332473003/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1332473003/80001

[commit-bot: I haz the power, 2015-09-08 21:46:04]

Committed patchset #5 (id:80001) as
http://src.chromium.org/viewvc/chrome?view=rev&revision=296604

[eae, 2015-09-10 23:48:23]

This is awesome, thank you!