Can you update the reST docs?

@merwok I added a clause to whatsnew/3.7.rst. ensurepip.rst seems to explicitly not mention the dependencies it installs for pip (Before this PR, this was only setuptools), so I didn't change it.

Ok I’ll let @ncoghlan say if these should be implementation details or advertised features.

What packages (other then pip) this installs is an implementation detail. The intent was that once pip is able to automatically install setuptools/etc as part of building a sdist, that ensurepip would no longer ship setuptools by default, and it would only install pip.

Thanks for the PR! As @dstufft noted, the fact ensurepip installs even setuptools as a dependency is currently considered an implementation detail, and is likely to be replaced at some point by having pip itself dynamically install it when asked to build from a source archive (at which point pip would install both setuptools and wheel).

So I'm going to close this PR without merging it, but I've closed the related issue as "postponed" rather than "rejected", as there other reasons we may end up offering an ensuresetuptools module that bundles both setuptools and wheel: https://bugs.python.org/issue31634#msg303734