virtualenv, sys.path and site-packages
it seems that the pip process quit prematurely due to a package in requirements that could not be found.  this left things in limbo, stuck in the temp-like "build" folder before having a chance to complete the process which gets them into the proper "site-packages" location.
i am setting up a virtualenv for django deployment.  i want an isolated env without access to the global site-packages.  i used the option --no-site-packages, then installed a local pip instance for that env.
after using pip and a requirements.txt file i noticed that most packages were installed in a "build" folder that is not in sys.path so i am getting an error such as 
"no module named django.conf"
i also installed virtualenvwrapper after the base virtualenv package.
as far i as i can recall i have not seen a "build" folder before, and am curious why these packages weren't simply installed in my local env's site-packages folder.  how should i go about pointing to that build folder and why does it exist?
thanks