$ git clone -n https://src.fedoraproject.org/rpms/cross-gcc.git /var/lib/mock/f42-build-side-1-3501725-45976/root/chroot_tmpdir/scmroot/cross-gcc
Cloning into '/var/lib/mock/f42-build-side-1-3501725-45976/root/chroot_tmpdir/scmroot/cross-gcc'...
$ git fetch origin ebcad74d3cbed2fcda57a7aa0c67d7b47c3f9f1f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/cross-gcc
 * [new ref]         ebcad74d3cbed2fcda57a7aa0c67d7b47c3f9f1f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ebcad74 drop upstreamed patch