py-pyqt4: fix for the depends_lib reset caused by the Python PortGroup

[Joshua Root]

On 2016-12-18 04:58 , René J.V. Bertin wrote:
> On Sunday December 18 2016 04:38:30 Joshua Root wrote:
>
>> py-pyqt4 doesn't need qt4-mac.
>
> Correct.
>
>> The python portgroup's behaviour is correct.
>
>
> In this case it has the appropriate side-effect, but that doesn't make the behaviour right.
> It's not up to an essentially random portgroup to decide whether or not the port including it needs Qt4 or any other dependency that might already have been declared. If a port doesn't require a given dependency it shouldn't include portgroups that declare that dependency.

I really can't imagine the scenario in which it's wrong. If you include 
the python portgroup and have a name of the form py-something, you're 
asking for this behaviour.

- Josh