If origin/HEAD resolves to `master`, depot_tools can check if
origin/main exists. If so, it's very likely that origin/HEAD should be
updated to point to origin/main.
In the worst case, this will result in extra git remote call while not
changing local state (i.e origin/HEAD remained unchanged).

R=gavinmak@google.com

Bug: 1190702
Change-Id: I51e69d7a95d3534e1820099b4b6983d38b5e2763
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2795075Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>