core: use a custom filter for rendering all mako templates.

- brings old pylons function that converted None into a empty markup

rhodecode/config/middleware.py

@@ -273,6 +273,11 b' def includeme(config):'
     if asbool(settings.get('appenlight', 'false')):
         config.include('appenlight_client.ext.pyramid_tween')
 
+    if not 'mako.default_filters' in settings:
+        # set custom default filters if we don't have it defined
+        settings['mako.imports'] = 'from rhodecode.lib.base import h_filter'
+        settings['mako.default_filters'] = 'h_filter'
+
     # Includes which are required. The application would fail without them.
     config.include('pyramid_mako')
     config.include('pyramid_beaker')

rhodecode/lib/base.py

@@ -27,6 +27,7 b' controllers'
 import logging
 import socket
 
+import markupsafe
 import ipaddress
 import pyramid.threadlocal
 
@@ -570,6 +571,17 b' class BaseController(WSGIController):'
         return WSGIController.__call__(self, environ, start_response)
 
 
+def h_filter(s):
+    """
+    Custom filter for Mako templates. Mako by standard uses `markupsafe.escape`
+    we wrap this with additional functionality that converts None to empty
+    strings
+    """
+    if s is None:
+        return markupsafe.Markup()
+    return markupsafe.escape(s)
+
+
 class BaseRepoController(BaseController):
     """
     Base class for controllers responsible for loading all needed data for