report_charge() is not called when join
value is NULL. However, active_checked happens in search().
As a result, active_verify =1 and wrong guess is implied
(see previous commit). So active_verify is wrongly zeroed.
Placing null_empty check before active_checked check
in search(). This might have implications that we do
not realise now: so this is an EXPERIMENTAL fix.
User-space tests successful.