$ git clone -n https://src.fedoraproject.org/rpms/mingw-libpng.git /var/lib/mock/f40-build-2211683-52225/root/chroot_tmpdir/scmroot/mingw-libpng
Cloning into '/var/lib/mock/f40-build-2211683-52225/root/chroot_tmpdir/scmroot/mingw-libpng'...
$ git fetch origin eddc34ac46f753039f7d8fd5f8dc0d15d3eaad61:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mingw-libpng
 * [new ref]         eddc34ac46f753039f7d8fd5f8dc0d15d3eaad61 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at eddc34a Update to 1.6.40