Revert "Revert PR #708."

This reverts commit 70e311b43f.

letsencrypt-apache/setup.py

@@ -1,3 +1,5 @@
+import sys
+
 from setuptools import setup
 from setuptools import find_packages
 
@@ -5,12 +7,16 @@ from setuptools import find_packages
 install_requires = [
     'acme',
     'letsencrypt',
-    'mock<1.1.0',  # py26
     'python-augeas',
     'zope.component',
     'zope.interface',
 ]
 
+if sys.version_info < (2, 7):
+    install_requires.append('mock<1.1.0')
+else:
+    install_requires.append('mock')
+
 setup(
     name='letsencrypt-apache',
     packages=find_packages(),