Eliminate a unit test warning while running tests with earlier versions of Python.

setup.py

@@ -70,6 +70,22 @@ if sys.argv[-1] == 'publish':
 long_description = make_long_description()
 template_files = ['*.mustache', '*.txt']
 
+# We follow the suggestion here for compatibility with earlier versions
+# of Python:
+#
+#   http://packages.python.org/distribute/python3.html#note-on-compatibility-with-setuptools
+#
+if sys.version_info < (2, 7):
+    extra = {}
+else:
+    # For testing purposes, we also use use_2to3 with Python 2.7.  This
+    # lets us troubleshoot the absence of package resources in the build
+    # directory more easily (e.g. the absence of README.rst), since we can
+    # troubleshoot it while using Python 2.7 instead of Python 3.
+    extra = {
+        'use_2to3': True,
+    }
+
 setup(name='pystache',
       version='0.5.0-rc',
       license='MIT',
@@ -87,7 +103,6 @@ setup(name='pystache',
           'pystache.tests.data.locator': template_files,
       },
       test_suite='pystache.tests',
-      use_2to3=True,
       entry_points = {
         'console_scripts': ['pystache=pystache.commands:main'],
       },
@@ -99,5 +114,6 @@ setup(name='pystache',
         'Programming Language :: Python :: 2.5',
         'Programming Language :: Python :: 2.6',
         'Programming Language :: Python :: 2.7',
-      )
+      ),
+      **extra
 )