Temporarily revert test case from
a2b70c89ca1a5fcf6181d3c777d82e7b83d2de1b.
That code patch was good as far as it went, but the associated test case
has exposed fundamental brain damage in the parallel scan mechanism,
which is going to take nontrivial work to correct. In the interests of
getting the buildfarm back to green so that unrelated work can proceed,
let's temporarily remove the test case.