$ git clone -n https://src.fedoraproject.org/rpms/ghc-aeson-yaml.git /var/lib/mock/f41-build-840167-160595/root/chroot_tmpdir/scmroot/ghc-aeson-yaml
Cloning into '/var/lib/mock/f41-build-840167-160595/root/chroot_tmpdir/scmroot/ghc-aeson-yaml'...
$ git fetch origin be62210129cef0a75e90494465c77b0dc0216d75:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-aeson-yaml
 * [new ref]         be62210129cef0a75e90494465c77b0dc0216d75 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at be62210 refresh .cabal revision