[pca] chkmin ignoring obsoletions if an older version of the patch is installed

[Martin Paul]

Ateeq Altaf wrote:
> I've made the following addition to not overwrite a higher patch rev with a
> lower one in the code, which I think should address the problem but not sure
> if it's too simple and I've missed something:

Your fix is perfectly fine, and I've integrated it into my version of "chkmin".

Seems as if you're the first to come across this issue - thanks a lot for 
reporting it and providing a fix!

Martin.