If you place a boat and fence on the same block it will fall through

When a boat is placed on the same block as a fence it will fall through the floor in all biomes except ocean. 
how to recreate 

1. put any type of fence down creating a line or pen
2. Put any boat on the same black as one of the fences
3. the boat falls through the floor

when this happens the boat only falls through the first block rendering unusable until dug out.