Crap. This is more complicated - I just oversaw the dynamic nature of the came_from targets - different buttons yield different came_from targets, namely their `href` attributes.

That's the reason why the link to the login and register forms were previously patched using `adhocracy.overlay.rebindCameFrom`. The `came_from` parameter has always gotten lost if a validation error occured, as it isn't stored in the POST data. The same problem now exists here, but without validation error. Best would be to actually put it in the POST data (patch a hidden field instead of a link using the same javascript function), but IIRC this caused problems with the `repoze.who.friendlyform`, but I might be completly wrong).