Assert failure on running a completed portal again

Hi,

I notice that the following Assert in PortalRun fails when a same portal is
executed more than once by an Execute message whose "max number of rows"
is specified to zero, that is, "no limit".

/* Set run_once flag. Shouldn't be clear if previously set. */
Assert(!portal->run_once || run_once);
portal->run_once = run_once;

I tested this using pgproto [1] in Pgpool-II.

I believe the server should return CommanComplete normally in this case.
his can be fixed by not setting execute_is_fetch flag (run_once as the result)
when the portal is already completed since no rows will be fetched in this case.
I've attached a pach in this approach.

[1] https://www.pgpool.net/docs/latest/en/html/pgproto.html

Regards,
Yugo Nagata

--
Yugo Nagata <nagata(at)sraoss(dot)co(dot)jp>