The trace is :
Somme developpers use non ascii characters (like "é" or "à") in their commit messages.
These messages are then read by Hudson and dispalyed on build pages. It's when CiConnector class read these pages that the error occur.
Mainly, it's because of the SaxReader and how it reads the response stream.
I've modififed the classe CiConnector to deal with Hudson "badly" encoded HTML pages, by changing the line
The patch is attached if interested.