Mojira Archive
MC-70010

Double plants can be placed at and grow at y = 255 resulting in incomplete double plant

The bug

Double plants can be placed at and grow (by using bonemeal on grass (tallgrass type=tall_grass) or on fern (tallgrass type=fern)) at y = 255 resulting in an incomplete double plant.

Other two block high blocks like doors cannot be placed at y = 255.