This reverts commit a645fa4ffb.
It is really devstack causing problems here; it was removing the
python-virtualenv package & re-installing using pip (see depends-on).
This failed because the pip-install we did here removed the egg-file
that rpm expected to be there, so rpm bailed out on the removal.
But even if it worked, this just leads you back down the path of the
original problem; that the system packaged version can be re-installed
and overwrites the pip installed version. Thus I still believe this
is the correct thing to do in the dib element.
Note it is not a common problem (devstack aside); most jobs don't
touch python-virtualenv & related packages (the one we did notice this
on was being brought over from travisci where it was required for some
reason).
Change-Id: I82acb865378a0fa5903a6267bfcee0e2962eced0
Depends-On: Ib0edf6c4ee8a510e9d671213de35d787f56acfed
995c539491