$ git clone -n https://src.fedoraproject.org/rpms/xerces-j2.git /var/lib/mock/f40-build-2138767-50843/root/chroot_tmpdir/scmroot/xerces-j2
Cloning into '/var/lib/mock/f40-build-2138767-50843/root/chroot_tmpdir/scmroot/xerces-j2'...
$ git fetch origin b07b2ffc7765599286acfede55e8fae3224a7bf7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xerces-j2
 * [new ref]         b07b2ffc7765599286acfede55e8fae3224a7bf7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b07b2ff Update javapackages test plan to f40