Need to check 21.4.

Reported by Marcus Harnisch:

 > Our d-c-r returns a coding system object like this: 
 >  
 > #<coding-system undecided undecided(do-eol do-coding) eol-type=lf> 
 
(defun-when-void find-coding-systems-region (start end &optional buffer) 
  (list (coding-system-name 
         (detect-coding-system start end &optional buffer)))) 
 
 >  
 > Also in contrast to the doc string d-c-r doesn't seem to return a list 
 > of these objects. At least not if there is only one coding system. 
 >  
 > The FSF function #'find-coding-systems-region returns an actual list 
 > of symbols, like (undecided). So it seems Aidan's response was 
 > correct, we don't have such a thing.