The scripts still work with Python 2.
There are no intended behaviour changes.

Bug: 939847
Change-Id: Icada60c5b2cf351d62aead26b7364fcef2c2a3e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1524486Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Raul Tambre <raul@tambre.ee>