title: ccache BASEDIR (shared) configuration
body: <p>Environment is Ubuntu 12</p>
  
  <p>I have two different versions of the same build.  </p>
  
  <p>one located under /media/CM10/custom
  the other under /home/malachi/CM10/android/system</p>
  
  <p>I have a specialized build-setup.sh which is invoked by the main build process and they each have:</p>
  
  <p>CCACHE_BASEDIR=/media/CM10/custom</p>
  
  <p>and</p>
  
  <p>CCACHE_BASEDIR=/home/malachi/CM10/android/system</p>
  
  <p>However it is definitely not sharing between the two.  The cache size is about 3.9GB when I do the one, and stays there if I repeat.  If I do the other, it grows it to over 7GB.</p>
  
  <p>When i check the ccache logs, it appears to be picking up the base dir and rewriting the relative paths.  Any clues how to get ccache to properly share between these two?  Thank you</p>