Do not call the stream function again after it has failed

Should fix #32

src/fellow_cache.c

@@ -3909,7 +3909,8 @@ fellow_cache_obj_iter(struct fellow_cache *fc, struct fellow_cache_obj *fco,
 	if (derefn)
 		fellow_cache_seg_deref(deref, derefn);
 
-	if ((flags & OBJ_ITER_END) == 0) {
+	if ((flags & OBJ_ITER_END) == 0 &&
+	    (fcr.status == fcr_ok && fcr.r.integer == 0)) {
 		ret2 = func(priv, OBJ_ITER_END, NULL, (size_t)0);
 		if (fcr.status == fcr_ok && fcr.r.integer == 0)
 			fcr.r.integer = ret2;