Ticket is
https://fedorahosted.org/389/ticket/47823
Fix is
https://fedorahosted.org/389/attachment/ticket/47823/0003-Ticket-47823-at...
Taking into account Rich reviews that simplify the handling of plugins
config, that is now in the pblock SLAPI_PLUGIN_PRIVATE.
Thank you very much for these tips.
Test case is
https://fedorahosted.org/389/attachment/ticket/47823/0002-Ticket-47823-te...