The test was failing because the wait for currentOp.inprog to become
non-empty was too generous, and would accept "whatsmyuri" (for example)
instead of the query we are trying to wait for. Check for our namespace
and for a "$where" query so we only proceed into the real test after the
parallel query has started.
It was impossible to tell what went wrong in this test when
it failed, and it almost always worked. Now, the sequence of
events leading to a failure will be much more obvious.
