>Make sure you don't have a file called vnd0 or vnd0d in the current directory.

This seems sorta crazy.  I would assume that the sane default would be to
assume that I want a device, and the system knows where devices come from.

Having vnconfig check . is like having the shell check for a file called
"./stdout" if I type "2>&1".  If I want to specify a file in the current
directory, I can.

This behavior makes the by-far-most-common case unpredictable.  That seems
bad.  The Principle of Least Astonishment dictates that devices should be
taken from /dev by default.

Compare with, say, opendisk(3).

-s