title: Can't use virtualenv without sudo or user-specific install and reconfig
body: <p>I would like to have a system-wide install of virtualenv on my debian jessie server, usable by each user without requiring sudo (the way it should work anyway) or user-specific installation.</p>
  
  <p>Here's what I type from scratch:</p>
  
  <pre><code>$ sudo apt-get install python3
  #Install OK
  $ sudo apt-get install python3-pip
  #Install OK
  $ pip3 install virtualenv
  #Fails with "error: could not create '/usr/local/lib': Permission denied"
  $ sudo pip3 install virtualenv
  #Install OK, but it appears that '/usr/local/bin' now has 'drwxr-s---'
  #permissions instead of 'drwxrwsr-x' (users can't list files in the directory...)
  $ virtualenv env1
  #Fails with "Command not found" (virtualenv is in '/usr/local/bin')
  $ sudo virtualenv env1
  #OK, but that's not the way it should work
  </code></pre>
  
  <p>I can get it to work with a user specific installation (<code>pip3 install --user virtualenv</code>) and some $PATH initialisation in "~/.bashrc" but it's a bit laborious for each user to have to install and reconfigure virtualenv.</p>
  
  <p>I'm sure I'm missing something, but it seems pip3 is not setting the permissions properly on the files and folders it creates in '/usr/local' when I run the command to install virtualenv.</p>