Again, sys.path shouldn't ever be exported into PYTHONPATH :)

R=eakuefner@chromium.org, nodir@chromium.org, vadimsh@chromium.org

Bug: 825290,825174
Change-Id: Ia0594da3ff25972a08fdf74ae2aef5be79cbf3af
Reviewed-on: https://chromium-review.googlesource.com/978594Reviewed-by: Ethan Kuefner <eakuefner@chromium.org>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>