use '.py' suffix in a temporary file for pylint.

otherwise pylint-1.2.0 seems not working.

product/ERP5Type/Utils.py

@@ -470,7 +470,7 @@ def checkPythonSourceCode(source_code_str):
     sys.stderr = cStringIO.StringIO()
     sys.stdout = cStringIO.StringIO()
 
-    with tempfile.NamedTemporaryFile() as input_file:
+    with tempfile.NamedTemporaryFile(suffix='.py') as input_file:
       input_file.write(source_code_str)
       input_file.seek(0)