Unblock the client when we can't find an upstream

If we can't find an upstream, we keep the client around, so it needs to
be unblocked.

servers/lloadd/operation.c

@@ -773,5 +773,5 @@ fail:
     op->o_client_refcnt--;
     operation_destroy_from_client( op );
     CLIENT_UNLOCK_OR_DESTROY(client);
-    return -1;
+    return rc;
 }