Send a typed revision expression to cat-file --batch over stdin and
parse its object header and exact byte length. This safely resolves the
commit OID and retrieves its raw message in one Git process instead of
separate rev-parse and cat-file calls.
Bug: 553599402
Change-Id: I764894323ec28e134f2523bd1d5694738b6b52d0
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/623903
Reviewed-by: Brian Gan <brgan@google.com>
Tested-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>
