(PUP-2642) Make default in selector be out of band, raise error nomatch

This makes the selector expression in the future evaluator have
the same semantics as the 3.6.1 current evaluator. The future evauator
did not process default out of band, and did not raise an error when
there was no match.

This fixes both problems.
Merge pull request #2687 from hlindberg/PUP-2642_selector-default-out-of-band

(PUP-2642) Make default in selector be out of band, raise error nomatch