$ git clone -n https://src.fedoraproject.org/rpms/rubygem-chunky_png.git /var/lib/mock/f45-build-34816-691/root/chroot_tmpdir/scmroot/rubygem-chunky_png
Cloning into '/var/lib/mock/f45-build-34816-691/root/chroot_tmpdir/scmroot/rubygem-chunky_png'...
$ git fetch origin 9bfba7e145c89f885256da6b061d8c793d9b2894:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-chunky_png
 * [new ref]         9bfba7e145c89f885256da6b061d8c793d9b2894 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9bfba7e Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild