Even on this site.
I want to draw attention to GitHub Bug #907
Many of us are reliant on openid, this seem to be a conflict with recent authentication code.
It is not to do with the lightopenid code as far as I cans see. I have used the existing version and the curl version and they both validate (some minor changes are need for shared hosting but that is expected).
I wonder if it is to do with the postback.