$ git clone -n https://src.fedoraproject.org/rpms/yash.git /var/lib/mock/f40-build-1951013-25188/root/chroot_tmpdir/scmroot/yash
Cloning into '/var/lib/mock/f40-build-1951013-25188/root/chroot_tmpdir/scmroot/yash'...
$ git fetch origin 9a88572793bfdabb8bc12f2f2e579919000ae969:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/yash
 * [new ref]         9a88572793bfdabb8bc12f2f2e579919000ae969 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9a88572 2.57