Turn off Python output buffering.
Turn off Python output buffering.

Running without the '-u' flag results in the output not appearing in the
Swarming task output.

My guess is that the script I added in
https://skia-review.googlesource.com/c/28840 is hanging asking for the
sudo password, but I can't tell due to the missing output.
Change-Id: I3caec445b3d6b0441cb1b94ea4c21120a6a1f726
Reviewed-on: https://skia-review.googlesource.com/30582
Reviewed-by: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>
Commit-Queue: 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