$ git clone -n https://src.fedoraproject.org/rpms/libpng.git /var/lib/mock/f45-build-16784-491/root/chroot_tmpdir/scmroot/libpng
Cloning into '/var/lib/mock/f45-build-16784-491/root/chroot_tmpdir/scmroot/libpng'...
$ git fetch origin 189b72618658df96aff1c66d3c746dc0d4818dad:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libpng
 * [new ref]         189b72618658df96aff1c66d3c746dc0d4818dad -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 189b726 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild