$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rttool.git /var/lib/mock/f45-build-35269-694/root/chroot_tmpdir/scmroot/rubygem-rttool
Cloning into '/var/lib/mock/f45-build-35269-694/root/chroot_tmpdir/scmroot/rubygem-rttool'...
$ git fetch origin b30dd014bccbfa862849e130681786a2e90f4a3e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rttool
 * [new ref]         b30dd014bccbfa862849e130681786a2e90f4a3e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b30dd01 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild