The place cache shared one lookup between callers but started it without a
signal or deadline, so a cancelled request kept running and stayed cached.
A shared lookup now has its own deadline, is cancelled when every caller has
given up, and only a successful answer is kept.
Brief sections received a named place as its bounding box, so they centered
on the box's middle: Tokyo's aircraft were sorted from a point in the
Pacific. Sections now receive the place name and resolve it like a direct
query, and place lookups are cached briefly so a brief resolves it once.
Sameh Khamis