- progress was set to 100 by every UpdateList, partial results included,
and never reset when a search started
- So a GET could report a new query, the previous result set, and
progress 100, and a client had no way to tell it was stale
- Now cleared where the search is requested and set to 100 only on the
final result. Query and the reset happen in the same locked section
that dumpStatus locks, so query == X with progress 100 means the
matches belong to X
Fix#4903
Junegunn Choi
7e6339979f