umlauts in passwords result in blank page

Dear SPIP team,

today, I used SPIP for the first time. As a diligent user, one of the 
first things I did was to change my password. I noted that if my 
password contains an umlaut (e.g. ü, u with trema), the password is not 
changed and a blank page is displayed instead. I would expect instead 
that my password is changed, and some confirmation displayed. Non-ASCII 
characters in passwords should provide no problem, especially for an 
application that makes internationalization a priority.

A second issue is that I haven't find a way to post a proper bug report 
on your website; hence the message to the mailing list.

Best,
Jonas