UserDB::Custom and Password::Custom loads module twice and calls init three times

Same issue as #2675 (closed) except that UserDB::Custom calls moduleLoad twice:

    eval $self->{p}->loadModule( $self->{conf}->{customUserDB} );                # init called here
    ($@)
      ? return $self->{p}->loadModule( $self->{conf}->{customUserDB} )           # init called here
      : die 'Unable to load UserDB module ' . $self->{conf}->{customUserDB};   

# init called after returning by outer loadModule

Also affects Password::Custom