East/West Pillars have shading error

Sideways pillars facing east/west have shading errors on top and bottom sides. Does not affect right-side-up pillars or north/south pillars.
Bug exists in both Fast and Fancy, in smooth lighting modes Minimum and Maximum, but not in Off. Extremely visible at night with a light source other than the sky and when affected block surfaces' are bordered by a block.
Hay bales and logs of any kind do not seem to be affected.
Affects 14w10a through 14w10c thus far.