$ git clone -n https://src.fedoraproject.org/rpms/rr.git /var/lib/mock/f39-build-2278916-55222/root/chroot_tmpdir/scmroot/rr
Cloning into '/var/lib/mock/f39-build-2278916-55222/root/chroot_tmpdir/scmroot/rr'...
$ git fetch origin 886e77a8198f36944a1c76be4d100266b580684c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rr
 * [new ref]         886e77a8198f36944a1c76be4d100266b580684c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 886e77a Rebase to rr-5.7.0.