Update the code to better reflect recommended style:

Use != instead of <> since <> is documented as "obsolescent".
Use "is" and "is not" when comparing with None or type objects.
diff --git a/Lib/dircache.py b/Lib/dircache.py
index a35e16d..08b127a 100644
--- a/Lib/dircache.py
+++ b/Lib/dircache.py
@@ -19,7 +19,7 @@
         mtime = os.stat(path)[8]
     except os.error:
         return []
-    if mtime <> cached_mtime:
+    if mtime != cached_mtime:
         try:
             list = os.listdir(path)
         except os.error: