Empty spaces on signs with colored text STILL say "null"

Whenever I use commands to create a sign with colored text, exit the world, and re-log, all of the empty lines on the sign are filled with the word "null"
(and yes, I did try replacing the signs)

This bug was written off as fixed with the release of snapshot 15w36d, but as you can see in the image below, it is not.

Hopefully this is a problem on my end