$ git clone -n https://src.fedoraproject.org/rpms/gnome-vfs2.git /var/lib/mock/f42-build-888033-188541/root/chroot_tmpdir/scmroot/gnome-vfs2
Cloning into '/var/lib/mock/f42-build-888033-188541/root/chroot_tmpdir/scmroot/gnome-vfs2'...
$ git fetch origin f17a3e8d8d1c802e6d253b585a3d4db5a1787c78:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-vfs2
 * [new ref]         f17a3e8d8d1c802e6d253b585a3d4db5a1787c78 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f17a3e8 fix FTBFS