automatically included.  Remove duplicate data file matches if both
include_package_data and package_data are used to refer to the same
files.
(merge from trunk)

--HG--
branch : setuptools-0.6
extra : convert_revision : svn%3A6015fed2-1504-0410-9fe1-9d1591cc4771/sandbox/branches/setuptools-0.6%4046791