convert returns tuple

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@34380 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/EmailDocument.py

@@ -457,7 +457,8 @@ class EmailDocument(File, TextDocument):
         part_encoding = part.get_content_charset()
         part_html = part.get_payload(decode=1)
         # Invoke Document class HTML stripper
-        html_result = self.convert(format='html', text_content=part_html,
+        mime, html_result = self.convert(format='html',
+                                         text_content=part_html,
                                          charset=part_encoding)
     if html_result:
       # Give priority to HTML