$ git clone -n https://src.fedoraproject.org/rpms/xorg-x11-drv-dummy.git /var/lib/mock/f41-build-860109-168801/root/chroot_tmpdir/scmroot/xorg-x11-drv-dummy
Cloning into '/var/lib/mock/f41-build-860109-168801/root/chroot_tmpdir/scmroot/xorg-x11-drv-dummy'...
$ git fetch origin 50e25ab4bd152122ca761d9e5a078a23dbca9ffd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xorg-x11-drv-dummy
 * [new ref]         50e25ab4bd152122ca761d9e5a078a23dbca9ffd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 50e25ab Clean up SPEC file