Kirill Reshke <reshkekirill(at)gmail(dot)com> writes:
> reproduced here on v13, v16, v18 and HEAD. Looks like we need to teach
> ExecAlterObjectSchemaStmt to respect allow_system_table_mods GUC.
allow_system_table_mods has never been intended to be bulletproof,
only to slow down careless superusers. I'm not especially concerned
about whether there are paths it doesn't cover.
regards, tom lane