$ git clone -n https://src.fedoraproject.org/rpms/glib2.git /var/lib/mock/f41-build-1019219-17967/root/chroot_tmpdir/scmroot/glib2
Cloning into '/var/lib/mock/f41-build-1019219-17967/root/chroot_tmpdir/scmroot/glib2'...
$ git fetch origin 5c3a4f6541cd2e58e8dca6b291c048ff383db916:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/glib2
 * [new ref]         5c3a4f6541cd2e58e8dca6b291c048ff383db916 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5c3a4f6 Remove extra blank line from spec file