Bug report for 8.2.3c:
When org-agenda-sorting-strategy is set to deadline-up (or similar
values), the Global Todo list always places non-timestamped entries at
the beginning, even when org-sort-agenda-notime-is-late is true. This
is inconsistent with the behavior when org-agenda-sorting-strategy is
time-up.
I believe the problem is that the org-cmp-ts function copied a line from
the older org-cmp-time function:
(def (if org-sort-agenda-notime-is-late 9901 -1))
9901 is later than all times of day, but not later than all date/time
stamps.