Previously little bits of the scm.GIT were mocked (like SetConfig,
and GetConfig, but not the other config related methods).
This changes things so that the git config state is a class whose
logic is shared between prod and test, with a 'real' and 'test'
implementation which know how to load and save configuration at
a low level.
R=yiwzhang
Change-Id: I1dc11b550908862607ea539de7fa60fbce30e700
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5660891
Commit-Queue: Yiwei Zhang <yiwzhang@google.com>
Reviewed-by: Allen Li <ayatane@chromium.org>
Auto-Submit: Robbie Iannucci <iannucci@chromium.org>
Reviewed-by: Yiwei Zhang <yiwzhang@google.com>