$ git clone -n https://src.fedoraproject.org/rpms/ceph.git /var/lib/mock/f42-build-864573-172456/root/chroot_tmpdir/scmroot/ceph
Cloning into '/var/lib/mock/f42-build-864573-172456/root/chroot_tmpdir/scmroot/ceph'...
remote: warning: refname 'HEAD' is ambiguous.        
$ git fetch origin 396c7768f72ec1dddc14d659cb6a9a48a4be7b4c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ceph
 * [new ref]         396c7768f72ec1dddc14d659cb6a9a48a4be7b4c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 396c776 remove openssl-engine