This reverts commit edb6e8c5.

Reason for revert: missing some py3 changes 

Original change's description:
> Add python3 support to bot_update recipe module
>
> Bug: 1227140
> Change-Id: Id4938c966da54957f84f59d0aef0c68c381ad5f6
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3016032
> Reviewed-by: Josip Sokcevic <sokcevic@google.com>
> Commit-Queue: Gavin Mak <gavinmak@google.com>

Bug: 1227140
Change-Id: If0852908b112ff6bdd4152189c7cb198eebd2c22
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3022309
Auto-Submit: Gavin Mak <gavinmak@google.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>