I try to update our v9c setup weekly, but it's causing a bit of a problem. We use a modified `main.py` file for the addon `payment_paypal` that works around issues with the return URL for Paypal. Everytime we update, this file is replaced with the original.

Before I go changing permissions and such in a semi-production setup (we're live testing with a few users), I wanted to ask everyone's opinion here. Suggestions?