IFS as the control variable in a for loop

[Grisha Levit]

When in a non-interactive shell, IFS, when modified as the control variable
in a for loop does not change splitting behavior.
$ bash -c 'for IFS in .; do printf "%s\n" "$IFS" "$*"; done' bash x x
.
x x

$ bash -ic 'for IFS in .; do printf "%s\n" "$IFS" "$*"; done' bash x x
.
x.x