$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rspec-mocks.git /var/lib/mock/f40-build-2639322-66352/root/chroot_tmpdir/scmroot/rubygem-rspec-mocks
Cloning into '/var/lib/mock/f40-build-2639322-66352/root/chroot_tmpdir/scmroot/rubygem-rspec-mocks'...
$ git fetch origin 284f768d3d10bc98657aa18819246e2abf2079e8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rspec-mocks
 * [new ref]         284f768d3d10bc98657aa18819246e2abf2079e8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 284f768 enable test again