[FIX] auth_signup: do not send email to duplicated user

When duplicating a user, an email was sent to a user at the email of the
previous user (as the create is called before changing the email).

Closes #8754

addons/auth_signup/res_users.py

@@ -279,3 +279,9 @@ class res_users(osv.Model):
             ctx = dict(context, create_user=True)
             self.action_reset_password(cr, uid, [user.id], context=ctx)
         return user_id
+
+    def copy(self, cr, uid, id, default=None, context=None):
+        if not default or not default.get('email'):
+            # avoid sending email to the user we are duplicating
+            context = dict(context or {}, reset_password=False)
+        return super(res_users, self).copy(cr, uid, id, default=default, context=context)