$ git clone -n https://src.fedoraproject.org/rpms/rubygem-backports.git /var/lib/mock/f45-build-34791-691/root/chroot_tmpdir/scmroot/rubygem-backports
Cloning into '/var/lib/mock/f45-build-34791-691/root/chroot_tmpdir/scmroot/rubygem-backports'...
$ git fetch origin 7f8f24ee630b8bb3ab29f7aba57ea85c1fad227b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-backports
 * [new ref]         7f8f24ee630b8bb3ab29f7aba57ea85c1fad227b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7f8f24e Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild