Ensure our requirements validator understands we are stuck with what …

…we get in python6

requirements/test-requirements-py26.txt

@@ -1,4 +1,4 @@
 # Requirements for developing on python 2.6
-astroid<=1.3.2
+astroid<=1.3.2 # rq.filter: >=1.3.2,<1.3.3
 pylint<=1.3.0 # rq.filter: >=1.3,<1.3.1
 -r test-requirements.txt