Comment 39 for bug 37828

What I was getting at is that a distro might want to be able to display more scripts than just the user's chosen locale (e.g. Ubuntu includes fonts for many different scripts in the default install). From this point of view, having Indic/Arabic text display correctly in non Indic/Arabic locales is desirable (especially in the web browser).

There is one modification to my steps to reproduce the bug: if using DejaVu to reproduce the bug, you must use a version < 2.5. The latest version doesn't include "liga" table entries for the ligatures in question, so the bug is not triggered (it seems that the change to the font was made because of this bug).