[autoroll] Break git locks before starting DEPSLocal parent
[autoroll] Break git locks before starting DEPSLocal parent

This was left out and is causing problems on a roller.

Change-Id: I47f0a82fe59d417d8d91f3fa7269f846296b885e
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/466276
Reviewed-by: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>
Commit-Queue: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot