pg_class.reltype -> pg_type.oid missing for pg_toast table

I have a memory of the catalog not being MVCC,

so maybe this is normal and expected,

but I wanted to report it in case it's not.

When copying all tables in pg_catalog, to a separate schema with the purpose

of testing if foreign keys could be added for all oid columns, I got an error for a toast table:

ERROR:  insert or update on table "pg_class" violates foreign key constraint "pg_class_reltype_fkey"

DETAIL:  Key (reltype)=(86987582) is not present in table "pg_type".

CONTEXT:  SQL statement "

    ALTER TABLE catalog_fks.pg_class ADD FOREIGN KEY (reltype) REFERENCES catalog_fks.pg_type (oid)

  "

The copies of pg_catalog were executed in one and the same transaction,

but as separate queries in a PL/pgSQL function using EXECUTE.

/Joel