Spawned from a core-mentorship thread about possibly outdated branch names in dev guide examples.

These are a few places that use real branch names in examples, and need to be kept current to make things easier for new contributors:

http://docs.python.org/devguide/committing.html#multiple-clones-approach
http://docs.python.org/devguide/setup.html#getting-the-source-code
http://docs.python.org/devguide/devcycle.html#summary

Another couple of items:

- one early one (before actually making the release) to check that the latest released version of pip has been bundled into CPython (that's supposed to happen when pip is released, but it's worth double checking)

- there's a missing entry for the RM confirming they have the go ahead from the Mac Expect before proceeding with a release