Well, so I decided to switch to Python3. I wanted to use the source code. This was harder than I thought due to outdated, misleading, missing or hard-to-find documentation.
The most obvious road to follow is a very recent post by Joel (http://www.makehumancommunity.org/forum/viewtopic.php?f=9&t=12448), but this will give you the deprecated source code (Bitbucket) without telling you. EDIT: I finally realized that this posting is rather old, so Joel is not to blame. Anyway a good reason to update this thread.
My next attempt was to look at http://www.makehumancommunity.org/wiki/Releases. The pages dealing with 1.2.0 contained a subsection called "running from source" without telling you where to get the source. I edited these pages. Now they do.
I finally found what I was looking for at http://www.makehumancommunity.org/content/downloads.html, but at the wrong place. The link to Github is in the section "stable version", which is simply wrong. You still find the stable version on Bitbucket. Github will give you Python3.