That error message should only occur when you run kinit -k without 
specifying a client principal name on the command line.

Since you clearly are specifying a principal name, my best guess is 
that we introduced an argument parsing bug on Windows when we added 
getopt_long() support to the Unix build (in commit 
8f9ade8ec50cde1176411085294f85ecfb2820a4 on Feb 24 2016).  
Specifically, I suspect the "optind" variable as seen by kinit is not 
set correctly after the call to getopt_long().

Unfortunately, I don't currently have the ability to investigate 
further without spending a lot of time spinning up a Windows 
development environment.