on non-linux systems bash is not the default shell (by default) and
lives in a completely different path

Change-Id: I6580c776dda1b60b3d5c5f5f1ce4d6694ac45fe9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1605902Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>