fuse: don't keep all Archive() instances around
fuse: don't keep all Archive() instances around

they're only needed inside process_archive, and not needed in general
for pending_archives.

RonnyPfannschmidt/borg,RonnyPfannschmidt/borg,RonnyPfannschmidt/borg,RonnyPfannschmidt/borg,edgewood/borg,RonnyPfannschmidt/borg,edgewood/borg,edgewood/borg,edgewood/borg