frontend.py: Fix function argument

Previosly in function was passed raw value 'self.ignore_dirs', not a list as expected 'ignore_dirs'.

Fixes for python-babel#832

Author: Edwin18

babel/messages/frontend.py

@@ -458,7 +458,7 @@ def finalize_options(self):
 
         ignore_dirs = listify_value(self.ignore_dirs)
         if ignore_dirs:
-            self.directory_filter = _make_directory_filter(self.ignore_dirs)
+            self.directory_filter = _make_directory_filter(ignore_dirs)
         else:
             self.directory_filter = None