Revert of Delete lots of svn logic from bot_update (patchset #5 id:80001 of https://codereview.chromium.org/2280213002/ )

Reason for revert:
Everything's purple :(

Original issue's description:
> Delete lots of svn logic from bot_update
>
> R=hinoka@chromium.org
> BUG=472386
>
> Committed: https://chromium.googlesource.com/chromium/tools/depot_tools/+/082267a659f94bf7bca5cb144e203ca0913abb3a

TBR=hinoka@chromium.org,hinoka@google.com,iannucci@chromium.org,agable@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=472386

Review-Url: https://codereview.chromium.org/2320653003