cursor: allow command responses that do not have "ok" field.

Author: Christian Hergert

src/mongoc/mongoc-cursor.c

@@ -454,14 +454,15 @@ _mongoc_cursor_unwrap_failure (mongoc_cursor_t *cursor)
       }
       RETURN(true);
    } else if (cursor->is_command) {
-      if (_mongoc_rpc_reply_get_first(&cursor->rpc.reply, &b)) {
-         if ( bson_iter_init_find(&iter, &b, "ok") &&
-              bson_iter_as_bool(&iter)) {
-            RETURN (false);
-         } else {
-            _mongoc_cursor_populate_error(cursor, &b, &cursor->error);
-            bson_destroy(&b);
-            RETURN (true);
+      if (_mongoc_rpc_reply_get_first (&cursor->rpc.reply, &b)) {
+         if (bson_iter_init_find (&iter, &b, "ok")) {
+            if (bson_iter_as_bool (&iter)) {
+               RETURN (false);
+            } else {
+               _mongoc_cursor_populate_error (cursor, &b, &cursor->error);
+               bson_destroy (&b);
+               RETURN (true);
+            }
          }
       } else {
          bson_set_error (&cursor->error,