Improvement: End the generic trial instead of clearing it when a subs…

[AntonioDiPassio-AppSys]

This will end the generic trial instead of clearing it, which enables you to still know if a user had a generic trial or not (and when it ended)

[taylorotwell]

Not going to risk a breaking change here.

[AntonioDiPassio-AppSys]

Actually, the introduction of this piece of code (in #1628) caused a breaking change in my application.

Regardless of that, how would my pull request be a breaking change?
It serves the same purpose as the changed code: making sure there is no generic trial when a subscription is started.
But it is more logical to end the ongoing generic trial at that moment instead of just clearing it (making it seam there was never a generic trial in the first place)

@driesvints Can you back me up on this one please?

[driesvints]

I'm sorry @AntonioDiPassio-AppSys but looks like Taylor doesn't wants to merge this right now. Since we only got one report for this we're gonna let things be.