Comment 21 for bug 1196932

Patch commit message:

    Fix handling of DELETE obj reqs with old timestamp

    The DELETE object REST API was creating tombstone files with old
    timestamps, potentially filling up the disk, as well as sending
    container updates.

    Here we now make DELETEs with a request timestamp return a 409 (HTTP
    Conflict) if a data file exists with a newer timestamp, only creating
    tombstones if they have a newer timestamp.

    The key fix is to actually read the timestamp metadata from an
    existing tombstone file (thanks to Pete Zaitcev for catching this),
    and then only create tombstone files with newer timestamps.

    We also prevent PUT and POST operations using old timestamps as well.