Re: pg_upgrade and materialized views

Well, the attached script reproduces the issue.

Make a scratch dir somewhere, cd into it, and run it. It will download
9.6.7 and 10.2, build them, create a test db in 9.6.7, modify it a bit
here and there to get to the desired state, pg_upgrade it to 10.2 and
vacuum.

Might even be a good idea to create a regression test with that, but
AFAIK there's nothing remotely like that in the current tests.

The patch you propose makes the test succeed. It may be true that
there might be other similar issues lurking in that code, but it looks
like it fixes this particular issue.