- Fixed improper handling of IF_MODIFIED_SINCE header

  inside Five/browser/resource.py

doc/CHANGES.txt

@@ -4,6 +4,13 @@ Zope Changes
   Change information for previous versions of Zope can be found in the
   file HISTORY.txt.
 
+  Zope 2.11.6 (2009/12/30)
+
+    Bugs Fixed
+
+      - Fixed improper handling of IF_MODIFIED_SINCE header
+        inside Five/browser/resource.py
+
   Zope 2.11.5 (2009/12/22)
 
     Bugs Fixed

lib/python/Products/Five/browser/resource.py

@@ -83,7 +83,7 @@ class FileResource(BrowserView, Resource):
         # HTTP If-Modified-Since header handling. This is duplicated
         # from OFS.Image.Image - it really should be consolidated
         # somewhere...
-        header = request.environ.get('If-Modified-Since', None)
+        header = request.environ.get('HTTP_IF_MODIFIED_SINCE', None)
         if header is not None:
             header = header.split(';')[0]
             # Some proxies seem to send invalid date strings for this