Merge pull request #414 from tpltnt/enforce-py2-setup

enforce Python 2.7 during installation

setup.py

@@ -27,6 +27,11 @@ def read_version_py(infname):
         if mo:
             return mo.group(1)
 
+# make sure we have a proper version of python
+if 2 != sys.version_info.major:
+    raise RuntimeError("Python version 2 is required")
+
+# source all the other data
 VERSION_PY_FILENAME = 'src/allmydata/_version.py'
 version = read_version_py(VERSION_PY_FILENAME)