$ git clone -n https://src.fedoraproject.org/rpms/xalan-c.git /var/lib/mock/f42-build-862926-171252/root/chroot_tmpdir/scmroot/xalan-c
Cloning into '/var/lib/mock/f42-build-862926-171252/root/chroot_tmpdir/scmroot/xalan-c'...
$ git fetch origin 12a0a5d16d40f9b9d3f2aab918b1c6416039786d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xalan-c
 * [new ref]         12a0a5d16d40f9b9d3f2aab918b1c6416039786d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 12a0a5d Invoke %cmake in %conf rather than in %build