title: Why does pip list not work correctly within a virtual environment created by pipx?
body: <p>I'm on a Linux/Ubuntu system, in a folder designated by pyenv as Python 3.8.1. I've install pipx using <code>pip install pipx</code>. If I install an application (cowsay), and activate the virtual environment for the application, pip lists my globally installed packages. <strong>Why I'm I not seeing the site packages for the cowsay install when the virtual environment is activated?</strong></p>
  <p>You can see from the example below that <code>pip list</code> gives me the same result regardless of the activation status of the virtualenv? I know that during project development, this is not the observed response. When inside a venv, pip list gives me the site packages installed in the venv.</p>
  <pre><code>pipx --verion
  0.15.5.1
  
  pip --version    
  pip 20.2.3 from /home/steve/.pyenv/versions/3.8.1/lib/python3.8/site-packages/pip (python 3.8)
  
  
  cd /home/steve/.local/pipx/venvs/
  source activate cowsay/bin/activate
  
  (cowsay):~/.local/pipx/venvs$ pip list
  Package     Version
  ----------- --------
  argcomplete 1.12.1
  click       7.1.2
  distro      1.5.0
  packaging   20.4
  pip         20.2.3
  pipx        0.15.5.1
  pyparsing   2.4.7
  setuptools  41.2.0
  six         1.15.0
  userpath    1.4.1
  (cowsay) :~/.local/pipx/venvs$ deactivate
  
  :~/.local/pipx/venvs$ pip list
  Package     Version
  ----------- --------
  argcomplete 1.12.1
  click       7.1.2
  distro      1.5.0
  packaging   20.4
  pip         20.2.3
  pipx        0.15.5.1
  pyparsing   2.4.7
  setuptools  41.2.0
  six         1.15.0
  userpath    1.4.1
  </code></pre>