BUG #15263: pg_dump / psql failure. When loading, psql does not see function-based constraints or indices

The following bug has been logged on the website:

Bug reference: 15263
Logged by: Brian Ceccarelli
Email address: ceccareb(at)talusmusic(dot)com
PostgreSQL version: 10.4
Operating system: Red Hat Enterprise Linux 7.5
Description:

This problem is easy to duplicate.

I have a database with a table with a function-based check constraint.
The database has another table with a function-based index.
I dump with COPY statements (the default).

When I load the database from the dump I just created, loading (via psql)
logs error messages. Postgres cannot find functions inside the function the
constraint or index invokes. You will see. The following zip file
contains a schema that caused the problem. Just create a database and run
dumpfailureexample.sql. pg_dump the database. psql to load the
database. The load log is dumpfailureexample.log.

http://talussoftware.com/docs/dumpfailure.zip

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I discovered this problem when I dumped a Postgres 9.6.2 DB to a 10.4 DB.
When I dump using 9's version of pg_dump, the subsequent load works. When
I dump using 10's pg_dump, the subsequent load fails.