Text on glowing signs no longer looks different to text on normal signs

Using a glow ink sac on a sign makes the text glow as usual, but no longer gives it its unique glowing look.

How to reproduce:

1. Place a sign and write some text on it.
2. Use a glow ink sac on it.

Expected result:

The text on glowing signs would have a border around it like in previous versions.

Observed result:

The text on glowing signs look identical to the text on normal signs.