Above-ground biomes randomly alternate on the y-axis near biome borders

Steps to Reproduce:  

1. Create a New World (Or use the seed I randomly got which is 3287837387583955118)

2. Set the Biome Blending setting to Off

3. Enable the ‘biome’ Debug Screen Text

4. Find a point where two biomes meet (On my seed, an example location is -26 64 129)

5. Break blocks below you

Observed Results:  

The biome keeps changing every few blocks

Expected Results:  

Biomes are consistent vertically (Excluding verticality-reliant biomes such as the several cave biomes)