stop warning about removals from IA

In a test, I uploaded a pdf, and several files were derived from it.
After removing the pdf, the derived files went away after approximatly
half an hour. This window does not seem worth warning about every time.
Documented it in the tip.

Remote/S3.hs

@@ -278,18 +278,11 @@ retrieveCheap _ _ _ = return False
  - While it may remove the file, there are generally other files
  - derived from it that it does not remove. -}
 remove :: S3Info -> S3Handle -> Remover
-remove info h k = warnIARemoval info $ do
+remove info h k = do
 	res <- tryNonAsync $ sendS3Handle h $
 		S3.DeleteObject (T.pack $ bucketObject info k) (bucket info)
 	return $ either (const False) (const True) res
 
-warnIARemoval :: S3Info -> Annex a -> Annex a
-warnIARemoval info a
-	| isIA info = do
-		warning "Derived versions of removed file may still be present in the Internet Archive"
-		a
-	| otherwise = a
-
 checkKey :: Remote -> S3Info -> Maybe S3Handle -> CheckPresent
 checkKey r info Nothing k = case getpublicurl info of
 	Nothing -> do
@@ -345,7 +338,7 @@ retrieveExportS3 r info _k loc f p =
 		return True
 
 removeExportS3 :: Remote -> S3Info -> Key -> ExportLocation -> Annex Bool
-removeExportS3 r info _k loc = warnIARemoval info $
+removeExportS3 r info _k loc = 
 	catchNonAsync go (\e -> warning (show e) >> return False)
   where
 	go = withS3Handle (config r) (gitconfig r) (uuid r) $ \h -> do