>> 1. M-: (setq org-agenda-window-frame-fractions '(1.0 . 1.0)) RET
>> 2. M-x org-agenda a
>>
>> Expected results: The *Org Agenda* buffer occupies the entire frame
>> Actual results: The *Org Agenda* buffer occupies the entire frame EXCEPT
>> for a five line window at the top of the frame
>
> Due to fact that `fit-window-to-buffer' no more deletes other windows by
> side-effect.  Hence for the '(1.0 . 1.0) case `org-fit-agenda-window'
> (or `org-fit-window-to-buffer') should call `delete-other-windows' or
> something the like.

Hi,

this bug s fixed in the Org git repository.  The fix will move into Emacs eventually.

- Carsten