Eli Bendersky firstname.lastname@example.org added the comment:
I've incorporated your suggestions except the new formulation for verbosity to doctest.testmod, since it's not really clear which one is more accurate. I think it's intelligible as it is now (especially given that test.support is for use of Python contributors, and not random users). If you have strong preferences about it, feel free to commit another formulation.
I answered your comments in the code review tool. Regarding the use of assertEqual for the floating point results, I just didn't want to rely on the exact representation of these values. I'm not 100% sure Python ensures this is true on all platforms it supports. Recall that I was just replacing the fcmp code which did basically the same, also not comparing exactly.
I will commit a fixed patch to default. I see no reason to backport this since test.support is just a tool for core-devs and contributors and is mainly used for future developments.