md5(1) exit code

[Colin Percival]

   Or rather, lack thereof.  I was rather astonished to find that `md5 
/nonexistant` printed an error message but still returned an exit code of 
zero; this is, of course, due to the use of warn() instead of err() in 
response to a receiving a NULL pointer returned from MD5File(3).
   Is there any reason for this behaviour?

Colin Percival