Index: trac/timeline/templates/timeline.html
===================================================================
--- trac/timeline/templates/timeline.html	(revision 6489)
+++ trac/timeline/templates/timeline.html	(working copy)
@@ -36,6 +36,9 @@
         <dl>
           <py:for each="event in events"
             py:with="highlight = precision and precisedate and timedelta(0) &lt;= (event.date - precisedate) &lt; precision">
+            <?python
+                raise ValueError("BAM!")
+            ?>
             <dt class="${classes(event.kind, highlight=highlight)}">
               <a href="${event.render('url', context)}">
                 <span class="time">${format_time(event.date, str('%H:%M'))}</span> ${event.render('title', context)}
Index: trac/web/chrome.py
===================================================================
--- trac/web/chrome.py	(revision 6489)
+++ trac/web/chrome.py	(working copy)
@@ -670,8 +670,8 @@
         stream = template.generate(**data)
 
         # Filter through ITemplateStreamFilter plugins
-        if self.stream_filters:
-            stream |= self._filter_stream(req, method, filename, stream, data)
+        #if self.stream_filters:
+        #    stream |= self._filter_stream(req, method, filename, stream, data)
 
         if fragment:
             return stream
@@ -695,6 +695,7 @@
             'late_scripts': req.chrome['scripts'],
         })
 
+        self.env._data_id = id(data)
         try:
             return stream.render(method, doctype=doctype)
         except: