First of all we need to install needed packages
apt-get install libapache2-mod-wsgi python-virtualenv python-setuptools
Once we have installed the required packages proceed to create the Python environment
mkdir /usr/local/trac cd /usr/local/trac virtualenv python
We now have the isolated Python environment locate under /usr/local/trac/python.
To make possible to use easy_install with repositories we need to upgrade easy_install. I use this to install Trac plugins directly from SVN.
/usr/local/trac/python/bin/easy_install -U trunk
We now can install trac 0.12 using the 0.12b1 SVN Tag (http://svn.edgewall.com/repos/trac/tags/trac-0.12b1 or Trac==0.12b1) or directly from SVN Trunk:
This will download and install the latest trunk version for Trac.