Vines appear incorrectly mirrored when viewed from behind

For a comprehensive list of other examples of issues with 2D planes in models not being mirrored as expected, click here.

The bug

The planes composing vines do not mirror on the back as one would expect, resulting in physical/illogical weirdness.

Fixed model (Mojang has full permission to use this fix):

This issue did not exist up when vines were introduced, and was introduced with the fixing of MC-48512 in 14w10a.

How to reproduce

1. Place a vine on a sufficiently visually transparent block or hanging

2. View the jutting out pixels on the bottom right of the vine texture

3. View the exact same section of the vine on the direct opposite side

4. Note that the exact texture pattern at that position is different, even though it should be the same