[m-rev.] for post-commit review: simplify a predicate

[Mark Brown]

Hi Zoltan,

On Sat, Jun 4, 2016 at 2:47 AM, Zoltan Somogyi
<zoltan.somogyi at runbox.com> wrote:
> For review by anyone.
>
> The new code succeeds under a slightly different set of conditions
> than the old one, but I think the new test is the correct one.

That looks fine.

Mark