Dropped files

A request for a channel the page is still scanning, on the website: answered later rather than waited for. Python cannot wait inside a request with the page's other requests answered meanwhile -- one of them taking a lock the suspended one holds, or suspending in turn, freezes the only thread (plexora/_work.py checkpoint) -- so the route says "again in retry_ms" (RETRY_HEADER) and the worker puts the request back in its queue, behind whatever arrived meanwhile (workers/pythonWorker.js).