Comment 1 for bug 780812

software-center-agent was already updated to provide the supported distroseries as part of the fix for bug 917109 which was done to be able to fix the USC bug 833982 (which is quite related to this).

As a result, at least for precise, when the user views their previous purchases, they will only have an install button if their series is supported, in which case it is safe to replace the distroseries segment of the purchased deb_line with the current distroseries, afaict.