Handle encoded and non-encoded filenames

Yaws issue 378 was due to incorrect handling of percent-encoded
filenames. The fix for that in commit bc691ea led to the problem
described in commit 866f363, but that commit again broke 378. To
handle both issues, change yaws_api:url_decode_with_encoding/2 to
employ the unicode decoding approaches from both commits.

src/yaws_api.erl

@@ -796,16 +796,17 @@ url_decode_with_encoding(Path, Encoding) ->
     DecPath1 = case Encoding of
                    latin1 ->
                        DecPath;
-		   undefined ->
-                       case unicode:characters_to_list(list_to_binary(DecPath)) of
-                           UTF8DecPath when is_list(UTF8DecPath) -> UTF8DecPath;
-                           _ -> DecPath
-                       end;
 		   _ ->
-                       case unicode:characters_to_list(DecPath, Encoding) of
+		       try unicode:characters_to_list(list_to_binary(DecPath)) of
                            UTF8DecPath when is_list(UTF8DecPath) -> UTF8DecPath;
                            _ -> DecPath
-                       end
+		       catch
+			   error:badarg ->
+			       case unicode:characters_to_list(DecPath, Encoding) of
+				   UTF8DecPath when is_list(UTF8DecPath) -> UTF8DecPath;
+				   _ -> DecPath
+			       end
+		       end
                end,
     case QS of
         [] -> lists:flatten(DecPath1);