1.7 beta seagrass display issue

Verification builds:

Ver. 1.7 Build 111790

Summary:

When displayed in game normal seagrass and tall seagrass are not showing as they should this is using 1.7beta vanilla assets and with custom resource pack applied. 

Tall seagrass model is using the same texture top and bottom The bottom texture should be seagrass_doubletall_bottom_a.png and the top texture should be seagrass_doubletall_top_a.png and b variant.

Short is using the bottom of the tall seagrass instead of its own texture. Short seagrass uses seagrass.png usually but it is now using the bottom texture of the tall seagrass seagrass_doubletall_bottom_a.png this is incorrect.

Impact:

It looks really aesthetically bad/broken even in vanilla textures. 

Repro Steps:
Load a world got to seabed/riverbed and look at the animated seagrass. ** 

Observed Results:
Seagrass is not showing correctly both short and tall versions are not using the correct textures.

Expected Results:
Seagrass textures should be displayed as intended and shown as in previous versions.

Screenshots/Videos attached: Yes/No

Regression Build

This was working in 1.5 and 1.6 builds.

Notes: