Fix #3634 invalid return value from _weakref.ref(Exception).__init__

Reviewers: Amaury, Antoine, Benjamin
diff --git a/Objects/weakrefobject.c b/Objects/weakrefobject.c
index 5cd9173..9cdd021 100644
--- a/Objects/weakrefobject.c
+++ b/Objects/weakrefobject.c
@@ -326,7 +326,7 @@
     if (parse_weakref_init_args("__init__", args, kwargs, &tmp, &tmp))
         return 0;
     else
-        return 1;
+        return -1;
 }