whitespaces in include_vars

Hi all,

somewhere in the last week ansible 2.2 changed to fail on tabs in
include_vars files.
foo: 123 -- works
foo: 123 -- fails

Is that behaviour intentional? (I hope not. I thought I'm only a few
days away from being able to move from 1.9 to 2.x after the worst
performance problems got fixed...)
Did anyone see other places where different whitespaces show different
behaviour?

Thanks!

Harald