Steve Dower added the comment:
> Given specifying an encoding will do the same thing as universal_newlines would have, should I just "hide" references to universal_newlines in the doc? (i.e. only mention it under a versionchanged banner, rather than front-and-centre)

No. Don't hide universal_newlines, it's different than encoding.
universal_newlines uses the locale encoding which is a good choice in
most cases.