Rail Floating in a Mineshaft

Rail Floating in a Mineshaft 

There’s a chance that rail will floating in the air without the block on top of it.

How to Reproduce:

1.Found a Mineshaft with /locate mineshaft

2.Find further in Mineshaft

Expected Results
The rail should have a block on top of it 

Actual Results
Rail in results will floating.

This bug effect the gameplay and multiplayer.