Changing the texture of the space character changes the width of subtitles

The bug

If the space character is given a texture of a given width, this will affect the distance between subtitles and direction arrows, even though no space character is rendered there.

How to reproduce

A resource pack that gives space a wide texture is attached.

1. Download
2. Turn on subtitles
3. Note the gap size
4. Apply resource pack
5. Note the gap size

Expected results

The size would be the same.

Actual results

It is not.