The documentation makefile is missing support for Devhelp. The supplied patch fixes this for the Python 3 branch. It also edits the ouput of the sphinx build to change the name of the devhelp project. This is needed to be able to have both versions of documentation (py2 & py3) displayed in Devhelp. This is useful if developers need to access documentation for both versions, such as both maintaining a Python2 project and starting a new project in Python3. This has been patched in some distributions downstream, but would be nice to have patched upstream. See: https://bugs.launchpad.net/ubuntu/+source/devhelp/+bug/787039
I'm not sure that this belongs in core, but I'll certainly defer to Georg on that :). If it does go in, the help string should explain what 'devhelp' does, since it isn't obvious from the name (for a non-GNOME user...I had to google it).
I think we should avoid adding distro specific tools into CPython repository (and the another reason to reject this is that the other distros will probably want to add their tools).