script it's running.  This avoids it getting confused by projects with
non-standard distribution locations, and projects that may have various
eggs already sitting in their distribution directory.  It should probably
also do something like this for the build directory to ensure a clean,
fresh build, but it seems like overkill, since it only affects local
projects, not stuff that EasyInstall downloaded in the first place.

--HG--
branch : setuptools
extra : convert_revision : svn%3A6015fed2-1504-0410-9fe1-9d1591cc4771/sandbox/trunk/setuptools%4041111