diff -r 98399c347108 Lib/warnings.py
--- a/Lib/warnings.py	Thu Apr 29 22:34:25 2010 +0200
+++ b/Lib/warnings.py	Fri Apr 30 06:20:37 2010 -0400
@@ -216,9 +216,6 @@
         text = message
         message = category(message)
     key = (text, category, lineno)
-    # Quick test for common case
-    if registry.get(key):
-        return
     # Search the filters
     for item in filters:
         action, msg, cat, mod, ln = item
@@ -229,39 +226,40 @@
             break
     else:
         action = defaultaction
-    # Early exit actions
-    if action == "ignore":
-        registry[key] = 1
-        return
 
     # Prime the linecache for formatting, in case the
     # "file" is actually in a zipfile or something.
     linecache.getlines(filename, module_globals)
 
+    # Early exit actions
+    emit = key not in registry
     if action == "error":
         raise message
-    # Other actions
-    if action == "once":
-        registry[key] = 1
+    elif action == "ignore":
+        return
+    elif action == "once":
         oncekey = (text, category)
         if onceregistry.get(oncekey):
             return
         onceregistry[oncekey] = 1
-    elif action == "always":
-        pass
+        emit = True
     elif action == "module":
-        registry[key] = 1
         altkey = (text, category, 0)
         if registry.get(altkey):
             return
         registry[altkey] = 1
-    elif action == "default":
-        registry[key] = 1
-    else:
+        emit = True
+    elif action == "always":
+        emit = True
+    elif action != "default":
         # Unrecognized actions are errors
         raise RuntimeError(
               "Unrecognized action (%r) in warnings.filters:\n %s" %
               (action, item))
+    if not emit:
+        return
+    registry[key] = 1
+
     # Warn if showwarning() does not support the 'line' argument.
     # Don't use 'inspect' as it relies on an extension module, which break the
     # build thanks to 'warnings' being imported by setup.py.