A bucket carrying lifecycle config but no objects must produce a
successful sweep — no hangs, no errors, no dispatches. Pinned
because the bootstrap walker iterates bucket directories, and an
empty directory is a corner of that traversal that's easy to break
(slice-bounds bug on the first listing returning zero entries).
Asserts: worker logs "loaded lifecycle for" and "shards 0-15
complete", no FATAL output, bucket still exists after the sweep.
Chris Lu
7948f7a945