$ git clone -n https://src.fedoraproject.org/rpms/gjs.git /var/lib/mock/f40-build-2253695-54218/root/chroot_tmpdir/scmroot/gjs
Cloning into '/var/lib/mock/f40-build-2253695-54218/root/chroot_tmpdir/scmroot/gjs'...
$ git fetch origin 50f36b8c90943e50b3ecec58b2282f056c2ca40a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gjs
 * [new ref]         50f36b8c90943e50b3ecec58b2282f056c2ca40a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 50f36b8 Update to 1.78.2