Comment 6 for bug 827576

The changes entries are built in lib/lp/soyuz/adapters/notification.py / fetch_information() by snagging the changelog_entry from the passed SPR.

This method is called many times in the notification code, it needs refactoring and its results caching. When we have a separate function that calculates the changes, we can pass in a previous_version so it returns an aggregated changes log.