Commit 0563a3a8 just introduced another instance of the same unsafe
testing methodology that appeared in 2ac3ef7a, which I corrected in
257d8157.  Robert/Amit, please stop doing that.

Also look through the rest of f0e44751's test cases, and correct some
other queries with underdetermined ordering of results from the system
catalogs.  These haven't failed in the buildfarm yet, but I don't
have any confidence in that staying true.

Per multiple buildfarm members.