Git 2.32 added the %(describe) pretty placeholder. Use one log format to
retrieve both repo's describe string and commit date on newer clients,
with the existing describe-plus-log path retained for older Git and
untagged output.
Bug: 553599402
Change-Id: I108346030677b2b90ef8bfb5acea1c45be2c85f2
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/623904
Tested-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>
Reviewed-by: Brian Gan <brgan@google.com>
