rgw expiration problem, a bug ?

[Will Zhao <zhao6305@xxxxxxxxx>]

Hi all:
I found when I set the bucket expiration rule , after the expiration
date, when I upload a new object , it will be deleted , and I found
the related code like the following:
if (prefix_iter->second.expiration_date != boost::none) {
//we have checked it before
  Why  this should be true  ?   The new uploaded object should be deleted ?
is_expired = true;
} else {
is_expired = obj_has_expired(obj_iter->meta.mtime,
prefix_iter->second.expiration);
}