Coral wall fan texture planes are not correctly mirrored on the rear

The resource pack attached to MC-214691 offers a complete fix for this issue. Mojang have my full permission to (and are encouraged to) replace the affected vanilla model files with the contents of the resource pack.

The bug

The 2D planes which comprise the coral wall fan model are not mirrored as to appear the same depending on view direction.

How to reproduce

1. Look at one of the planes, taking note of its exact shape
2. Look at the exact same spot on that plane, but from behind
   1. Note how the texture is not the exact same at that point as it was from the previous viewpoint.

Expected behaviour

The rear faces would be mirrored in such a way that the texture appears the same, like is the case for blocks such as rails and vines.

Actual behaviour

The texture mapping is identical instead of flipped, resulting int hat region appearing different.

How to fix

The resource pack attached to MC-214691 fixes this issue completely.