$ git clone -n https://src.fedoraproject.org/rpms/glib2.git /var/lib/mock/f40-build-802591-144047/root/chroot_tmpdir/scmroot/glib2
Cloning into '/var/lib/mock/f40-build-802591-144047/root/chroot_tmpdir/scmroot/glib2'...
$ git fetch origin 03e2e263eb931a45344a9821e9b0ceec20286e7c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/glib2
 * [new ref]         03e2e263eb931a45344a9821e9b0ceec20286e7c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 03e2e26 Update to 2.80.0