title: Is a python virtual env supposed to be stand alone? If not, is there danger cross environment confusion?
body: <p>Working in my virtual environment, any import calls not resolved  in the virtual env will be resolved in the "original" environment is possible.  At the same time, 
  according to <a href="https://docs.python.org/3/tutorial/modules.html#intra-package-references" rel="nofollow noreferrer">https://docs.python.org/3/tutorial/modules.html#intra-package-references</a> , relative references are allowed.  I worry this could lead to confusion/conflicts with different versions of the same named objects entering or trying to enter a programs execution.  I am a novice to Python, and I am sure this issue is covered in documentation, but I can't find it.  Any pointers?</p>
  
  <p>Update 5/13/2017 - I found the following documention for python 3.6.1: <a href="https://docs.python.org/3/library/venv.html#creating-virtual-environments" rel="nofollow noreferrer">https://docs.python.org/3/library/venv.html#creating-virtual-environments</a></p>
  
  <blockquote>
    <p>On Windows, invoke the venv command as follows: </p>
    
    <p><code>c:\&gt;c:\Python35\python -m venv c:\path\to\myenv</code></p>
    
    <p><code>usage: venv [-h] [--system-site-packages] [--symlinks | --copies]
    [--clear] [--upgrade] [--without-pip] ENV_DIR [ENV_DIR ...]</code></p>
    
    <p><code>--system-site-packages:　Give the virtual environment access to the system              site-packages dir.</code></p>
  </blockquote>
  
  <p>The default is not to have access to the system site-packages directory.  Therefore I surmise that any code outside of the system site-packages directory is considered "safe enough" with respect to usage of relative import paths, and the user is responsible for not colliding with those items.  </p>