I'm happy to back off on this since it doesn't block texmanager from being imported, and it won't work anyway if dvipng is missing.

I don't think `dvipng_hack_alpha` is a command that should be used externally. It's used within the module to decide whether to change the output from dvipng. It looks like matplotlib detects the presence of dvipng on startup and if it isn't present, it disables the use of the tex module anyway. So this shouldn't really have an effect.