9.1rc1 regression: EXPLAIN on information_schema.key_column_usage

Hi list,

It seems I have found a regression in PostgreSQL 9.1rc1 (from 9.0).

In many cases, running the following query fails:
db=# EXPLAIN select * from information_schema.key_column_usage;
ERROR: record type has not been registered

However, this is not always reproducible. It seems to occur more
likely on an empty database. At first I suspected uninitialized memory
access somewhere, but valgrind does not highlight anything obvious.
Trying to isolate the part of the view that causes the error also
didn't yield any results.

Similarly, information_schema.triggered_update_columns also
occasionally returns this error, but less reliably.

Regards,
Marti