Windows getting started issue errno 2 not such file or directory

[Kelly Fraser]

I'm very new to beets but when installing on windows and running the beet config -e command I got 

error: Could not edit configuration: [Errno 2] No such file or directory

Actually the file existed (I created it) but there was no editor environment variable set. 

I think this is a regression to this issue. 

https://github.com/beetbox/beets/pull/2717#issuecomment-340458002

I ran this command to correct this issue but would be great if the above fix was put back in. 

set EDITOR=notepad.exe 

Thanks, 

p.s. I was unable to set atom as my editor though i tried this first even providing the full path to atom