spec: Avoid failures when `STDOUT` is no TTY
spec: Avoid failures when `STDOUT` is no TTY

When using secret variables in Travis CI, the output gets filtered through a
helper process by default (called `redirect_io` strategy) and hence the `STDOUT`
is no longer a real TTY when running the specs. See [1].

[1]: https://github.com/travis-ci/travis-ci/issues/6018

athityakumar/colorls,athityakumar/colorls