Remove the PURE_PYTHON flag.

AccessControl can't support a pure Python version, as the pure Python
implementation of Acquisition/ExtensionClass can't be perfect enough
and isn't able to proxy class dict proxies.

setup.py

@@ -12,7 +12,6 @@
 #
 ##############################################################################
 
-import os
 from os.path import join
 import platform
 import sys
@@ -25,9 +24,8 @@
 # PyPy won't build the extension
 py_impl = getattr(platform, 'python_implementation', lambda: None)
 is_pypy = py_impl() == 'PyPy'
-is_pure = 'PURE_PYTHON' in os.environ
 py3k = sys.version_info >= (3, )
-if is_pypy or is_pure or py3k:
+if is_pypy or py3k:
     ext_modules = []
 else:
     ext_modules = [

src/AccessControl/tests/actual_python.py

@@ -70,9 +70,7 @@ def display(self):
     #    pass
     #else:
     #    assert 0, "expected indirect attribute creation to fail"
-
-    # This fails if PURE_PYTHON=1 is specified, i.e. if the pure python
-    # version of AccessControl, Acquisition and Persistence/persistent are used
+
     assert getattr(C, "display", None) == getattr(C, "display")
     delattr(C, "display")
 

tox.ini

@@ -9,6 +9,5 @@ deps =
     zope.testrunner
     ./develop/Persistence
     ./develop/RestrictedPython
-    .[test]
 setenv =
     PIP_NO_CACHE = 1