$ git clone -n https://src.fedoraproject.org/rpms/golang-github-dennwc-btrfs.git /var/lib/mock/f38-build-side-42-init-devel-1085229-29985/root/chroot_tmpdir/scmroot/golang-github-dennwc-btrfs
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-1085229-29985/root/chroot_tmpdir/scmroot/golang-github-dennwc-btrfs'...
$ git fetch origin af93d63b418bbb3817761e04f07944204537d201:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-github-dennwc-btrfs
 * [new ref]         af93d63b418bbb3817761e04f07944204537d201 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at af93d63 initial commit, closes rhbz#2198973