Wrong ligature is rendered for spaceship operator with Fira Code font

Some fonts (like Fira Code) have ligatures for C++ operators. The "spaceship operator" of C++ for example. However, Creator renders it wrongly, unless it's commented out. Example:

The wrong ligature is used. When commented out, it works fine:

I don't know what causes this. The only thing I found is this comment in the FiraCode bug tracker:

https://github.com/tonsky/FiraCode/issues/64#issuecomment-227499029