BUG #16386: drop contraint in inherited table is missing in pg_dump backup

The following bug has been logged on the website:

Bug reference:      16386
Logged by:          klement szabolcs
Email address:      szittya314@gmail.com
PostgreSQL version: 10.12
Operating system:   centos 7
Description:

create table b (aaa int primary key,bb date );
create table A (id int primary key) inherits (B);
alter table a alter column aaa drop not null;

after i made pg_dump and pg_restore the not null contraint isexist on table
a;