[task scheduler] Fix env for 'git cl patch'
[task scheduler] Fix env for 'git cl patch'

BUG=skia:5723

Change-Id: I4d2b08ae71087ac8fccdce174fafd42485363d14
Reviewed-on: https://skia-review.googlesource.com/3025
Commit-Queue: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>
Reviewed-by: Ben Wagner <3ef7217be91069877d94f7907ce5479000772cd3@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