Can no longer walk in gaps between diagonally arranged cobblestone walls

From 1.4 to 1.4.2, in any game mode, you were able to walk between the gap created between diagonally arranged stone walls:

#.. ..#
... ...
..# or #..

But in 1.4.4 and 1.4.5 you can't do that anymore. Is that by design or was that an unintended effect?