$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rspec-support.git /var/lib/mock/f40-build-2639335-66352/root/chroot_tmpdir/scmroot/rubygem-rspec-support
Cloning into '/var/lib/mock/f40-build-2639335-66352/root/chroot_tmpdir/scmroot/rubygem-rspec-support'...
$ git fetch origin 165fc5cbe21d8fdcb5aa69b90212cdca68220d29:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rspec-support
 * [new ref]         165fc5cbe21d8fdcb5aa69b90212cdca68220d29 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 165fc5c 3.13.1