The bug
The application of textures to most fence gates is very odd, especially in a closed state. The strangest mapping is seen on the face pointing towards the player who placed it. However, the texture mapping on the opposite side is completely normal.
How to reproduce
Download and apply the attached resource pack
Place an oak fence gate
Expected results
Smooth texture mapping.
Actual results
The texture mapping on the face of the gate which is angled toward the player who placed it is very bizarre. The opposite face, however, is completely fine.
Linked issues
Attachments
Comments

I'm forward resolving MC-229647 to this since this is more detailed.
Yes, it's a duplicate, but this describes the problem a LOT better.