Update contributor task to prevent error if author doesn't have any commit in upstream
Update contributor task to prevent error if author doesn't have any commit in upstream

Ref https://github.com/putaindecode/putaindecode.fr/pull/321

putaindecode/putaindecode.fr,revolunet/putaindecode.fr,revolunet/putaindecode.fr,putaindecode/putaindecode.io,putaindecode/putaindecode.fr,putaindecode/putaindecode.fr,revolunet/putaindecode.fr