python: 2.7.9rc1 devel

ensurepip is backported to 2.7.9; use that to get pip instead of staging pip and setuptools ourselves.
Just to note: The ensurepip module does not do anything terribly intelligent. It is almost exactly running ``pip install --no-index --find-links /tmp-dir/that/has/wheels/ pip setuptools``. Depending on what flags you pass to ensurepip other flags will be passed but this is the core functionality.

Some corrections about this thread:

*  Ensurepip will never downgrade an already installed pip, this is one of our design constraints. ``python -m ensurepip`` itself will only ensure that you have *a* version of pip installed, but it doesn't not look at what versions. ``python -m ensurepip --upgrade`` will ensure that you have a version at least as new as the one that was bundled with that particular version of Python but it will not downgrade them.
* Using ensurepip will mean you won't install a *newer* version than what was shipped with that particular version of Python unless you also do ``pip install --upgrade pip setuptools`` after you invoke ensurepip.
* It's unlikely we're going to stop shipping setuptools anytime soon, it's not actually required for ensurepip (pip can install from Wheels without setuptools installed) but we ship it because right now it's not reasonable to expect that ``pip install random-package`` will succeed without setuptools installed. If at some point we did Homebrew could just execute ``pip install --upgrade setuptools`` after using ensurepip.
* You touched on the fact that ensurepip won't ignore ``~/.pydistutils.cfg``, unless the other pip maintainers have a problem with it the next version of pip (6.0) will support this (which means the versions of Python that ship with that version of pip will do that by default).
* Since ensurepip is really just pip under the covers the reason you have to uninstall pip is because you have a broken installation of pip where the metadata files indicate that pip is installed, but you no longer have the binaries files. Nothing is really actionable here, just mentioning that fact.