sdiff vs. $EDITOR

[Dan Jacobson]

sdiff supposedly calls $EDITOR, when not needed too, and that always
fails.

$ for i in a b; do echo $i >| $i; done
$ EDITOR=ed sdiff -o c a b
a            | b
%r
sdiff: subsidiary program `ed' failed
$ sdiff --version
sdiff (GNU diffutils) 2.8.1