openerp.auth_signup function sets self to login_mode default instead of singup

When a user which is not yet registered clicks a sing up link from an email (something which ends in someithing like "#action=login&token=SomeToken&type=signup") he very often gets the login mask instead of the sign up mask. Re-clicking the link a few times eventually brings up the sign up mask.

I don't know why this happens but it looks like the problem is somewhere in the openerp.auth_signup function:

if (dbname) {
 self.rpc("/auth_signup/get_config", {dbname: dbname}).done(function(result) {
  self.signup_enabled = result.signup;
  self.reset_password_enabled = result.reset_password;
  if (!self.signup_enabled || self.$("form input[name=login]").val()) {
   self.set('login_mode', 'default');
  } else {
   self.set('login_mode', 'signup');
  }
 });
} else {
 self.set('login_mode', 'default');
}

In this part from the openerp.auth_signup function the first
   self.set('login_mode', 'default');
is triggered as self.signup_enabled is false as debugging showed me.

I haven't digged further as I think it would take me very long to understand why this happens also the page gets visited by a signup link which also clearly gets recognized by the function as for a short time or in debbuning mode with break points you see that first the correct sign up mask is set and then gets 'resetted' at the above shown line of code to the login mask.