$ git clone -n https://src.fedoraproject.org/rpms/xmvn-generator.git /var/lib/mock/f41-build-781152-13559/root/chroot_tmpdir/scmroot/xmvn-generator
Cloning into '/var/lib/mock/f41-build-781152-13559/root/chroot_tmpdir/scmroot/xmvn-generator'...
$ git fetch origin b3341398089853e6a5e004f9cb5bfc81c2708499:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xmvn-generator
 * [new ref]         b3341398089853e6a5e004f9cb5bfc81c2708499 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b334139 Switch to a newer %patch syntax