$ git clone -n https://src.fedoraproject.org/rpms/ghc-cached-json-file.git /var/lib/mock/f40-build-745030-111932/root/chroot_tmpdir/scmroot/ghc-cached-json-file
Cloning into '/var/lib/mock/f40-build-745030-111932/root/chroot_tmpdir/scmroot/ghc-cached-json-file'...
$ git fetch origin 1e1fa9848cbb26321a3ca587e3bb08074f0a509c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-cached-json-file
 * [new ref]         1e1fa9848cbb26321a3ca587e3bb08074f0a509c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1e1fa98 bump over fbrnch