establish installed dependency not in portfile

[db]

On 7 Oct 2017, at 15:41, db <iamsudo at gmail.com> wrote:
> On 7 Oct 2017, at 15:15, Jeremy Lavergne <jeremy at lavergne.me> wrote:
>> Something like `port dependents gcc7`
> I forgot to mention it.
> $ port rdependents gcc7
> gcc7 has no dependents.

It seems that gcc7 comes from portgroup compilers. From the logs I kept when upgrading, gcc7 seems to never have been built for building py-numpy before.