mdeliver/current/mdeliver.c:

    (deliver): In rev 1582 i changed this from using rename(2) to
    the recommended link(2) + unlink(2).  But in minc i was using
    open(2) + rename(2) instead, which is just as safe as link +
    unlink but with one advantage.  So switch to that model.

minc/current/minc:
    (store_message): Document the open + rename procedure and
    explain why it is used instead of link + unlink.