This reverts commit a834f39e.

Reason for revert:
https://bugs.chromium.org/p/chromium/issues/detail?id=1017367

Original change's description:
> presubmit_support: Fix tests on Python 3.
>
> Bug: 1009814
> Change-Id: I2c2a835fc4fa0a7fc9e68dfff680fb0beacb491e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1869535
> Reviewed-by: Anthony Polito <apolito@google.com>
> Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>

TBR=ehmaldonado@chromium.org,apolito@google.com

Bug: 1009814
Change-Id: I48907caeca9b9b32e4e3a7cb5a636280d017a4c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1877350Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>