[Do not print ExitExceptions
John Meacham <john@repetae.net>**20050420035028] hunk ./CharIO.hs 37
-runMain action = do 
-    Control.Exception.catch (action >> return ()) (\x -> putErrDie $ show x)
+runMain action = Control.Exception.catch (action >> return ()) $ \x -> case x of
+        ExitException _ -> throw x
+        _ -> putErrDie $ show x