title: upgradepkg uses wrong version of python for package installs
body: <p>I'm using slackware that has python 2.6 by default.  I've installed python 2.7 and successfully insatlled numpy and scipy and matplotlib into python 2.7 using slackbuilds and pip.  </p>
  
  <p>However, when I try to install pygame using:</p>
  
  <pre><code>upgradepkg --install-new pygame-1.9.1-x86_64-1sl.txz
  </code></pre>
  
  <p>it installs to python 2.6 (the txz came from pkgs.org)</p>
  
  <p>Is there a way to specify in <code>upgradepkg</code> which python version I want to us? I suppose the sure way is to unpack the pygame file, get into it and change some values, then repack it, then run the upgrade command again... but I don't really know what I'm doing so I wanted to see if there's a simpler way before I embark on that journey.</p>
  
  <p>UPDATE: I'm having the same problem with PyGTK, so I'm starting to think it's something in the settings of upgradepkg... haven't been able to word the question right on Google to come up with a solution</p>