Bootstrap script fails on Ubuntu 16.04

[ocaisa]

The error is

  File "/tmp/tmpa7s641/lib/python2.7/site-packages/distribute-0.6.49-py2.7.egg/pkg_resources.py", line 2430, in insert_on
    "with distribute. Found one at %s" % str(self.location))
ValueError: A 0.7-series setuptools cannot be installed with distribute. Found one at /usr/lib/python2.7/dist-packages
valueerror: A 0.7-series setuptools cannot be installed with distribute. Found one at /usr/lib/python2.7/dist-packages

It looks like the same issue as this one

[boegel]

(duplicate of #1798)