don't fail if pdftk is not found

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@35515 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/PDFDocument.py

@@ -231,8 +231,13 @@ class PDFDocument(Image):
         result[key] = value
 
       # Then we use pdftk to get extra metadata
+      try:
         command_result = Popen(['pdftk', tmp.name, 'dump_data', 'output'],
                                                   stdout=PIPE).communicate()[0]
+      except OSError:
+        # pdftk not found
+        pass
+      else:
         h = command_result
         line_list = (line for line in h.splitlines())
         while True: