unbreak code if first chunk is bigger than size_lines

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@35048 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5SyncML/Signature.py

@@ -389,7 +389,9 @@ class Signature(Folder, SyncCode, File):
     chunk = list()
     chunk.append(self.partial_xml.data)
     size = chunk[0].count('\n')
-    current = next = self.partial_xml.next
+
+    current = self.partial_xml
+    next = current.next
     while size < size_lines and next is not None:
       current = next
       size += current.data.count('\n')