[MERGE] Fix docstring for bzrlib.xml_serializer.escape_invalid_chars.

[Ian Clatworthy]

Ian Clatworthy has voted approve.
Status is now: Approved


For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C20090512231041.GA5208%40vernstok.nl%3E
Project: Bazaar