Re: ALTER TABLE lock downgrades have broken pg_upgrade

Or at least, it did until Simon decided that ALTER TABLE RESET
doesn't require AccessExclusiveLock.

Now you get a failure.

I haven't tried to construct a pre-9.1 database that would trigger
this, but you can make it happen by applying the attached patch
to create a toast-table-less table in the regression tests,
and then doing "make check" in src/bin/pg_upgrade.  You get this:

...
Restoring database schemas in the new cluster
                                                            ok
Creating newly-required TOAST tables                        SQL command failed
ALTER TABLE "public"."i_once_had_a_toast_table" RESET (binary_upgrade_dummy_option);
ERROR:  AccessExclusiveLock required to add toast table.

Failure, exiting