Be shell-safe with git-filter-branch use in update.py

Be shell-safe with git-filter-branch use in update.py

The command argument to git filter-branch --index-filter is always
passed to a shell. Even on Windows, this will be git bash. Use proper
quoting when building this argument.

BUG=697185
Review-Url: https://codereview.chromium.org/2743363003
Cr-Commit-Position: refs/heads/master@{#456579}
Committed: https://chromium.googlesource.com/chromium/src/+/391e842f5feab036653813d0d441c1d504a971e8

[Mark Mentovai, 2017-03-13 20:32:44]

mark@chromium.org changed reviewers:
+ agable@chromium.org

[agable, 2017-03-13 23:35:10]

lgtm

[Mark Mentovai, 2017-03-14 00:11:07]

The CQ bit was checked by mark@chromium.org

[commit-bot: I haz the power, 2017-03-14 00:11:49]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-14 02:20:48]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1489450267036170, "parent_rev":
"345a7614774506af8d576a396b4b95acc7fc63c7", "commit_rev":
"391e842f5feab036653813d0d441c1d504a971e8"}

[commit-bot: I haz the power, 2017-03-14 02:21:27]

Description was changed from

==========
Be shell-safe with git-filter-branch use in update.py

The command argument to git filter-branch --index-filter is always
passed to a shell. Even on Windows, this will be git bash. Use proper
quoting when building this argument.

BUG=697185
==========

to

==========
Be shell-safe with git-filter-branch use in update.py

The command argument to git filter-branch --index-filter is always
passed to a shell. Even on Windows, this will be git bash. Use proper
quoting when building this argument.

BUG=697185

Review-Url: https://codereview.chromium.org/2743363003
Cr-Commit-Position: refs/heads/master@{#456579}
Committed:
https://chromium.googlesource.com/chromium/src/+/391e842f5feab036653813d0d441...
==========

[commit-bot: I haz the power, 2017-03-14 02:21:28]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/391e842f5feab036653813d0d441...