With the new developments in setuptools, I suggest pinning to a known working set for setuptools and zc.buildout. The pip install suggested does not guarantee success.
I've introduced the following combination for us at GW20E: zc.buildout=2.2.5 and setuptools=7.0
Also this works most of the time:
python bootstrap.py -c myfile.cfg --version=2.2.5
Combined with pinning:
setuptools = 7.0
zc.buildout = 2.2.5
The setuptools could probably be a bit newer, but I personally have no clue why they are developing setuptools at the rate they are. Only know it causes A LOT of problems which personally pisses me off. Spend so much time on issues related to this.