Fix bug where searching musts=[A, A.B] ignored B.
Fix bug where searching musts=[A, A.B] ignored B.

The problem was that during the expansion of A, B would get added to
the `total` set. And then because B was already in total, it would
bail early instead of expanding, but that meant it got left out of
the final query. But this only happened sometimes since random set
ordering would sometimes expand B before A and everything was ok.
I think the best solution is to do this first pass that eliminates
ancestors. Furthermore, I realized that the entirety of expand_nested
hinged on this flawed logic and was otherwise completely redundant
for a simple list comprehension.

voussoir/etiquette,voussoir/etiquette,voussoir/etiquette