orignal_filename does not exists, source_reference is used to store the original filename

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@28947 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/File.py

+# -*- coding: utf-8 -*-
 ##############################################################################
 #
 # Copyright (c) 2002 Nexedi SARL and Contributors. All Rights Reserved.
@@ -163,7 +164,7 @@ class File(Document, CMFFile, ConversionCacheMixin):
     """
       get mime type from file name
     """
-    if fname == '': fname = self.getOriginalFilename()
+    if fname == '': fname = self.getSourceReference()
     if fname:
       content_type,enc = mimetypes.guess_type(fname)
       if content_type is not None: