$ git clone -n https://src.fedoraproject.org/rpms/rust-x509-cert.git /var/lib/mock/f42-build-3252938-41225/root/chroot_tmpdir/scmroot/rust-x509-cert
Cloning into '/var/lib/mock/f42-build-3252938-41225/root/chroot_tmpdir/scmroot/rust-x509-cert'...
$ git fetch origin 792f7c6219b3e89cb6a774b7cbe0251659453da7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-x509-cert
 * [new ref]         792f7c6219b3e89cb6a774b7cbe0251659453da7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 792f7c6 Initial packaging (rhbz#2329142)