I have finally isolated the issue and I have a set of steps that reliably cause the segfault:
CREATE TABLE parent_table ( custdob timestamp with time zone not null, closed BOOLEAN NOT NULL DEFAULT FALSE ) PARTITION BY RANGE (custdob);
CREATE TABLE default_partition ( custdob timestamp with time zone not null, CONSTRAINT dummy_check CHECK (custdob < '2019-08-02T00:00Z') );
-- This is needed for the crash, if I add this column when creating the table "default_partition" then I don't get the crash, but when it's added with an "ALTER TABLE" then I get the crash. ALTER TABLE default_partition ADD COLUMN closed BOOLEAN NOT NULL DEFAULT FALSE;
ALTER TABLE parent_table ATTACH PARTITION default_partition DEFAULT;
INSERT INTO parent_table VALUES ('2020-02-02 01:00:00+00:00', 'f');
