[sudo-users] SIGHUP signal with sudoedit

[Todd C. Miller]

This was fixed in sudo 1.8.21, from the NEWS file:

   A change made in sudo 1.8.15 inadvertantly caused sudoedit to
   send itself SIGHUP instead of exiting when the editor returns
   an error or the file was not modified.

It looks like sudo 1.8.16 is the latest that ships with Ubuntu 16.04
but you can download sudo 1.8.23 packages from:
    https://www.sudo.ws/download.html#binary

 - todd