revert r42894 as this hack didn't help to workaround a bug quickly.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@42940 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/PDFDocument.py

@@ -218,7 +218,7 @@ class PDFDocument(Image):
 
     command_result = None
     try:
-      command = ['/usr/bin/pdf2djvu', tmp.name]
+      command = ['pdf2djvu', tmp.name]
       try:
         command_result = Popen(command, stdout=PIPE).communicate()[0]
       except OSError, e: