avoid apparent unused import

Author: fredrikt

src/pyff/test/test_pipeline.py

@@ -8,7 +8,6 @@
 from mako.lookup import TemplateLookup
 from mock import patch
 
-# don't remove this - it only appears unused to static analysis
 from pyff import builtins
 from pyff.exceptions import MetadataException
 from pyff.parse import ParserException
@@ -21,6 +20,9 @@
 
 __author__ = 'leifj'
 
+# The 'builtins' import appears unused to static analysers, ensure it isn't removed
+assert builtins is not None
+
 
 class PipeLineTest(SignerTestCase):
     def run_pipeline(self, pl_name, ctx=None, md=None):