Able to walk through closed double fence gates attached to cobblestone walls.

You are able to walk through closed double fence gates when they are attached to cobblestone walls or mossy cobblestone walls when they're facing east/west. The point where you walk through is in between the fence gates. Double fence gates seem to work normally when attached to wooden fences though.

gatharian added
Steps to duplicate
-Place down gates and cobblestone wall to form a square. (see photo attached.)
You will be able to walk threw at least one of the gates from a certain side.