$ git clone -n https://src.fedoraproject.org/rpms/skychart.git /var/lib/mock/f39-build-1655550-40540/root/chroot_tmpdir/scmroot/skychart
Cloning into '/var/lib/mock/f39-build-1655550-40540/root/chroot_tmpdir/scmroot/skychart'...
$ git fetch origin 91ee701e6388fa0b89adda98f3dd44ada28dcba4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/skychart
 * [new ref]         91ee701e6388fa0b89adda98f3dd44ada28dcba4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 91ee701 Update to latest snapshot