I have a font I can't live without (some form of psychotic disability I guess) - Fixedsys
MacVim is the only editor I use and once I noticed that it supports ligatures I started working on the font (I didn't do the whole font, only added programming ligatures). Everything was nice and easy until snapshot-147 which broke these ligatures. Now a>=b looks like instead of
(the vertical alignment is fine, it's just my screenshotting abilities).

The change that ruined it is this: ee668a4 by @ichizok

I tried to debug this for a couple of days, but my understanding of CoreText is close to zero and I'm mostly wandering around printing different things. There's of course a possibility that there's something wrong with the font itself, but it works everywhere else (except for Konsole in Arch Linux, which is a known issue and in Windows Powershell), at least on MacOS. It works in TextEdit, which I suppose is a "reference implementation" of CoreText based editor.

I'm willing to invest some more time with proper guidance from someone who knows how all of this works. For now, the workaround is just take MMCoreTextView.m from snapshot-146 and slap it into the snapshot-153 source tree and rebuild. Works for me, but this is stupid.

Relevant issue from the font repository: kika/fixedsys#16