As an example here are two examples, one with a 16 pixel high glyph set, and another with 32. the font is the same in every way
16:

32:

This appears to be because of a magic number 2. Here and Here. Nothing seems like it needs that additional support, as the lines are already broken by the highest and lowest glyph and not by the fonts line height.
Removing this number gives us this:

As an example here are two examples, one with a 16 pixel high glyph set, and another with 32. the font is the same in every way
16:


32:
This appears to be because of a magic number 2. Here and Here. Nothing seems like it needs that additional support, as the lines are already broken by the highest and lowest glyph and not by the fonts line height.
Removing this number gives us this:
