Logs on Furnace

When i put a White log on the furnace and tap a brown one or other the new log will become the white log, and the same when i put a brown one and then i filled with white ones they become brown.

How to Produce the bug:
1) Get two different types of logs.
2) Make a Furnace and put one log on it.
3) Put a different type of log.
4) Log Transformation!