Ceph » rgw

To avoid a string copy in the common mkdir path, handles for proposed buckets currently are staged in the handle table, before being rejected. They need to be destaged, not just marked deleted (because deleted objects are now assumed not to be linked, as of beaeff059375b44188160dbde8a81dd4f4f8c6eb).

This triggered an unhandled Boost assert when deleting staged handles, as current safe_link mode requires first removing from the FHCache.