Since the original merge of this code
(04208e7c79) several things have
changed; particularly now we ship dib-run-parts as part of dib, not as
a separate package.
We setup $_LIB to point to the shipped library diretory via
pkg_resources lookups. We now call dib-run-parts (as mentioned,
shipped as a dib library now), source scripts, etc. via $_LIB and thus
do not rely on $PATH. Consequently we don't need this activation
part.
Which is helpful, because "venv" (as opposed to virtualenv) doesn't
have activate_this.py. So this fixes installation under that for
Python 3.
We update the functional tests to use the virtualenv_command exported
by the ensure-pip role, which will test the venv path. There is no
need for dib_python as we are Python 3 only now.
Change-Id: Iede929ea2d278008220aac8b1d678ba41eba0d8a
