$ git clone -n https://src.fedoraproject.org/rpms/ancient.git /var/lib/mock/f39-build-1501155-34822/root/chroot_tmpdir/scmroot/ancient
Cloning into '/var/lib/mock/f39-build-1501155-34822/root/chroot_tmpdir/scmroot/ancient'...
$ git fetch origin afa9b7c76897028b543548e4cb5bc4dba727efa8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ancient
 * [new ref]         afa9b7c76897028b543548e4cb5bc4dba727efa8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at afa9b7c Update to 2.1.1