$ git clone -n https://src.fedoraproject.org/rpms/golang-github-armon-circbuf.git /var/lib/mock/f38-build-side-42-init-devel-587518-26119/root/chroot_tmpdir/scmroot/golang-github-armon-circbuf
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-587518-26119/root/chroot_tmpdir/scmroot/golang-github-armon-circbuf'...
$ git fetch origin b85eb033d7683b6d728a0773922288abe1bc4b04:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-github-armon-circbuf
 * [new ref]         b85eb033d7683b6d728a0773922288abe1bc4b04 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b85eb03 SPEC cleanup