Glowstone crystal formations are missing their bottom layers

Glowstone crystal formations are generating differently as of 14w04a. Where they previously generated large 3 dimensional crystals, most clusters generated in 14w04a and after are now clipped to the top layer only (persisting in 14w08a). The result is significantly less glowstone in the nether.

To see the results open snapshot 14w03b and create a new world (I used the seed "GLOWSTONE" all caps, without quotes) and compare the crystals generated to those from 14w04a+ using the same seed.

I have attached screenshots showing the observed difference
I traveled to the Nether and used "/tp 4 64 8 55 20" to get the same position and direction for each screenshot.