bug#35624: log-view-diff regression

[Juri Linkov]

>> The next step is to implement 'window-start-marker' in bug#35860,
>> and set it to the second line, so after displaying the log buffer
>> the first line will be off-screen.
>
> Speaking about this approach... What happens when the whole log buffer is
> shorter than the window it's displayed in?

It was difficult for me to test this case because I rely heavily on ediff
for development, but ediff has been broken for a week in master.
It makes sense to revert changes that break some function completely
because currently ediff is unusable giving this error:

Debugger entered--Lisp error: (void-function nil)
  nil(#("..." 39 51 (face (diff-file-header diff-header) fontified t)) (list 
(lambda nil (add-hook 'ediff-after-quit-hook-internal (lambda nil (if 
(ediff-buffer-live-p #<buffer *Ediff Session Group Panel*>) 
(ediff-show-meta-buffer #<buffer *Ediff Session Group Panel*> 1))) nil 'local) 
(setq ediff-meta-buffer #<buffer *Ediff Session Group Panel*> 
ediff-meta-session-number 1) (setq ediff-merge-store-file nil) (setcar '(nil 
nil (#("..." 39 51 ...) nil) (#<marker ...> nil) (#<marker ...> nil)) 
ediff-control-buffer))))
  ediff-filegroup-action()
  funcall-interactively(ediff-filegroup-action)
  call-interactively(ediff-filegroup-action nil nil)
  command-execute(ediff-filegroup-action)

But I tried to do ediff's work manually, and can confirm now that
when the whole log buffer is shorter than the window then the patch
from bug#35860 still works correctly hiding the first line initially.