Steps
1. Have Iron Bars and Glass pane on a flat surface not touching any blocks on the side of it
2. Place a barrier block next to them.

Expected results: In 1.8.9 barrier blocks did not connect to Iron Bars or Glass panes when placed next to each other.

Actual results: In 1.9.2 Iron bars and Glass panes connect to the barrier block when placed next to it. This doesn't happen with any of the fences such and wood or cobble.