Generate shorter keys for WORM and URL, avoiding keys that are longer than used for SHA256, so as to not break on systems like Windows that have very small maximum path length limits.

Backend/URL.hs

@@ -32,10 +32,8 @@ backend = Backend
 
 {- Every unique url has a corresponding key. -}
 fromUrl :: String -> Maybe Integer -> Annex Key
-fromUrl url size = do
-	n <- genKeyName url
-	return $ stubKey
-		{ keyName = n
-		, keyBackendName = "URL"
-		, keySize = size
-		}
+fromUrl url size = return $ stubKey
+	{ keyName = genKeyName url
+	, keyBackendName = "URL"
+	, keySize = size
+	}