BUG #15000: Cache lookup failure

The following bug has been logged on the website:

Bug reference: 15000
Logged by: Thomas Kellerer
Email address: postgres(at)kellerer(dot)name
PostgreSQL version: 10.1
Operating system: CentOS release 6.6
Description:

We have a script that copies data from one database to another using pg_dump
(plain text format) and the pipes the output to psql

The script consistently fails with:

pg_dump: [archiver (db)] query failed: ERROR: cache lookup failed for
relation 16693
pg_dump: [archiver (db)] query was: SELECT tableoid, oid, conname,
pg_catalog.pg_get_constraintdef(oid) AS consrc, conislocal, convalidated
FROM pg_catalog.pg_constraint WHERE conr elid =
'16693'::pg_catalog.oid AND contype = 'c' ORDER BY conname

Postgres version is:
PostgreSQL 10.1 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.4.7 20120313
(Red Hat 4.4.7-18), 64-bit

Apparently I can't attach the script here, so it can be downloaded from:

https://sql-workbench.net/pg/localized_texts_cache_lookup_error.sh