isSuperseded only looked for chunks the event named that the filer no
longer holds. A file copied in through a mount logs a create while the
copy is still running: the mount flushes metadata with chunk uploads in
flight, so that chunk list can have holes. ChunkStreamReader stops at
the first hole, the multipart upload sends a short part ("ContentLength=
8388608 with Body length 4194304"), and since every chunk the event
names is still live the event was never superseded. The daemon retried
it forever and the offset never moved past it.
Treat chunks the filer has added since the event the same way. The
event that added them follows in the log and uploads the finished file.
Alex K
fffdb7cc75