smll bfx

saqc/lib/tools.py

@@ -338,7 +338,8 @@ def dropper(field, drop_flags, flagger, default):
     if drop_flags is None:
         drop_flags = default
     drop_flags = toSequence(drop_flags)
-    drop_mask = flagger.isFlagged(field, flag=drop_flags)
+    if len(drop_flags) > 0:
+        drop_mask |= flagger.isFlagged(field, flag=drop_flags)
     return drop_mask