Force virtualenv pip to be used

[Peter Otten]

Alec Taylor wrote:

> Running Ubuntu 16.10 with Python 2.7.12+ (default one) and virtualenv
> 15.0.3 (`sudo -H pip install virtualenv`). What am I doing wrong?
> 
>     $ virtualenv a && . "$_"/bin/activate && pip --version
>     New python executable in /tmp/a/bin/python
>     Installing setuptools, pip, wheel...done.
>     pip 9.0.0 from /usr/local/lib/python2.7/dist-packages (python 2.7)
>     $ /tmp/a/bin/pip --version
>     pip 9.0.0 from /usr/local/lib/python2.7/dist-packages (python 2.7)
>     $ /tmp/a/bin/python -c 'from pip import __file__; print __file__'
>     /usr/local/lib/python2.7/dist-packages/pip/__init__.pyc
> 
> PS: Running with regular Bash 4.3.46(1)-release in GNOME Terminal. When I
> activate the virtualenv this appears in my env output: VIRTUAL_ENV=/tmp/a
> 
> PPS: Cross-posted [yesterday] http://stackoverflow.com/q/40438089

What's in your PYTHONPATH?

$ export PYTHONPATH=/usr/lib/python2.7/dist-packages/
$ virtualenv a && . "$_"/bin/activate && pip --version
New python executable in a/bin/python
Installing setuptools, pip...done.
pip 1.5.4 from /usr/lib/python2.7/dist-packages (python 2.7)
(a)$ unset PYTHONPATH
(a)$ pip --version
pip 1.5.4 from /home/peter/a/local/lib/python2.7/site-packages (python 2.7)