Currently .../login/signup_form.html specifies a length of 25 chars for the city field, but the database schema only has 20 characters for the city name. In addition to that, there is currently no check in the signup code to trim fields to their maximum database lenghts. We should be using truncate_userinfo() on the $user object before doing anything else with it.

Tha attached patches fix the issue in 1.6.3+, 1.7+ and HEAD.

Saludos. Iñaki.