Fix pip on py3k-precise nodes

The puppet modules that run after install_puppet blows away the pip
installed pip and replaces it with distro pip. This becomes hard for
tox to reconcile when building a virtualenv with requirements which
declare a dependency on newer pip versions than got installed.

After setting up the script, remove the python-pip packages and
re-run the command to get current pip on the system.

Change-Id: Ie862cb35dd93cb655941ac556d2b07d5e6be9ca1
Merge "Fix pip on py3k-precise nodes"