Fix failing xapian test

Author: schlatterbeck

test/test_config.py

@@ -449,7 +449,7 @@ def testInvalidIndexerLanguage_xapian_missing(self):
 
         # need to delete both to make python2 not error finding _xapian
         del(sys.modules['xapian'])
-        if xapian._xapian in sys.modules:
+        if 'xapian._xapian' in sys.modules:
             del(sys.modules['xapian._xapian'])
 
         self.assertEqual(config['INDEXER_LANGUAGE'], 'NO_LANG')