FATAL: cache lookup failed for function 1003

Is this the right list for this? I'm off the 'net atm and can't easily 
check.

I'm running on self-built RHEL 4.

I built from cvs this morning, and get the above error. Running grep 
over the source doesn't show anything helpful to me.
The initdb command (sans --auth) works for psql (PostgreSQL) 7.4.6 so 
I'm guessing I'm close.

What might be the problem?

+ rm -rf /home/pgtest/postgres/data
+ mkdir -p --mode=0700 /home/pgtest/postgres/data
+ initdb --auth=trust
FATAL:  cache lookup failed for function 1003
child process exited with exit code 1
initdb: removing contents of data directory "/home/pgtest/postgres/data"
The files belonging to this database system will be owned by user "pgtest".
This user must also own the server process.

The database cluster will be initialized with locale en_AU.UTF-8.
The default database encoding has accordingly been set to UTF8.

fixing permissions on existing directory /home/pgtest/postgres/data ... ok
creating subdirectories ... ok
selecting default max_connections ... 100
selecting default shared_buffers/max_fsm_pages ... 24MB/153600
creating configuration files ... ok
creating template1 database in /home/pgtest/postgres/data/base/1 ...
real    0m1.088s
user    0m0.530s
sys     0m0.523s
[pgtest@bilby ~]$