$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rspec.git /var/lib/mock/f45-build-35223-694/root/chroot_tmpdir/scmroot/rubygem-rspec
Cloning into '/var/lib/mock/f45-build-35223-694/root/chroot_tmpdir/scmroot/rubygem-rspec'...
$ git fetch origin 4cc87c284f3520570d7b94600c23c1adac98e2bb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rspec
 * [new ref]         4cc87c284f3520570d7b94600c23c1adac98e2bb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4cc87c2 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild