Wheels are (as far as I understand) binary distributions, so they ought to contain everything, that gets put into site-packages. I don't think they make for good source packages. In particular, the jaxlib wheel contains a bunch of shared objects and almost none of the source that one can see on Github.
Instead of erroring out, we could try to check whether the homepage points to a git forge and try to generate a git-reference from that. Failing this, we might want to set source to something, that produces an error when read or when used as a variable, similar to how unknown licenses are handled. Regards, Leo
