Make auto-svn also configure the current svn branch (if any).

Make auto-svn also configure the current svn branch (if any).

With this change, and running 'git auto-svn' whenever starting work on a
new upstream branch, much git-svn confusion and mayhem can be avoided.
For example:

$ git checkout -b drover_2403 branch-heads/2403
$ git svn info --url
  svn://svn.chromium.org/chrome-internal/trunk/tools/build
  # git-svn still thinks it's dealing with trunk.
$ git auto-svn
...
$ git svn info --url
  svn://svn.chromium.org/chrome-internal/branches/2403/tools/build
  # That's better.

R=agable@chromium.org, amineer@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=296667

[Michael Moss, 2015-09-11 23:21:58]

The CQ bit was checked by mmoss@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-11 23:22:08]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1340733002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1340733002/1

[commit-bot: I haz the power, 2015-09-11 23:23:59]

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

[commit-bot: I haz the power, 2015-09-11 23:23:59]

Dry run: This issue passed the CQ dry run.

[agable, 2015-09-14 16:20:05]

lgtm

[Michael Moss, 2015-09-14 16:22:31]

The CQ bit was checked by mmoss@chromium.org

[commit-bot: I haz the power, 2015-09-14 16:22:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1340733002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1340733002/1

[commit-bot: I haz the power, 2015-09-14 16:24:59]

Committed patchset #1 (id:1) as
http://src.chromium.org/viewvc/chrome?view=rev&revision=296667