Doesn't refresh PNG which substitutes the expanded macro

[root@…]

Scenario:

1. Put [[DiaVisView(a.dia)]] to the wiki page.
2. Attach a diagram a.dia.
3. Autogenerated raster file a.png is created and displayed on the page.
4. Attach an updated diagram a.dia, replacing the old one.
5. Autogenerated raster a.png is updated in filesystem but the page shows the old one.

[root@…]

0.11/DiaVisView/DiaVisView.py

@@ -208 +208 @@
         if style:
             attr['style'] = '; '.join(['%s:%s' % (k, escape(v))
                                        for k, v in style.iteritems()])
-        result = tag.img(src=png_url + "?format=raw", **attr)
+        result = tag.img(src=png_url.replace("/attachment/", "/raw-attachment/"), **attr)
         if link is not None:
             result = tag.p(result, href=link or url,
                            style='padding:2; border:none')

[regis.patroix@…]

DiaVisView.py

@@ -14 +14 @@
 import re
 import subprocess
 import Image
+import time
 
 
 from genshi.builder import Element, tag
@@ -171 +172 @@
                 raise Exception('Dia execution failed.')
 
             (png_file_size, png_file_time) = os.stat(png_path)[6:8]
+            png_file_time = int(time.time()*1000000)
             # Based on attachment.py, insert
             db = self.env.get_db_cnx()
             cursor = db.cursor()