Drop stale support for missing duration.

apachedex/__init__.py

@@ -133,10 +133,8 @@ class GenericSiteStats(object):
 
   def accumulate(self, match, url_match, date):
     self.status[match.group('status')][date] += 1
-    duration = match.group('duration')
     self.apdex[date].accumulate(match)
-    if duration is not None:
-      duration = int(duration)
+    duration = int(match.group('duration'))
     if url_match is None:
       url = match.group('request')
     else: