BUG #16655: pg_dump segfault when excluding postgis table

The following bug has been logged on the website:

Bug reference:      16655
Logged by:          Cameron Daniel
Email address:      cam.daniel@gmail.com
PostgreSQL version: 13.0
Operating system:   Debian Buster
Description:        

I'm getting a segfault when trying to pg_dump a database containing the
postgis extension, but only when excluding the spatial_ref_sys table. I am
using Docker but the base image is standard Debian and Postgres is being
installed from the official APT repos.

The Docker config is here for reference -
https://github.com/ccakes/nomad-pgsql-patroni/

Reproduction steps: https://paste.rs/bHR
Backtrace: https://paste.rs/Ym3

The segfault appears to be in pg_dump, the server just logs "unexpected EOF
on client connection with an open transaction" and continues running fine
otherwise.

Let me know if there's any extra info I can provide