Added tag upstream. Explanation is in discussion at related bug #991967 here:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=991967#169 and here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=991967#174 Briefly, since we are currently shipping a fork of Xen-4.14 on our unstable, testing, and stable versions of the hypervisor to better support arm devices but there is an annoying bug also in x86 (amd64) in these versions, IMO we should 1) Notify upstream of the fork we are doing and 2) Notify our users, especially on the stable branch, that our version of Xen is actually a fork of Xen-4.14. I know this can be discovered by reading the changelog, but to find it one must go back to the unstable version that was released back in December of 2020 to find where the fork started. Not many people (including me) would look there to try to find such a significant change to the package, especially on stable where ordinarily only vanilla security patches from upstream are in the changelog. So, as a courtesy to our users, I think the visibility of this change needs to be elevated to the status of at least a README.Debian file, if not an actual notification to the user by dpkg when installing. Of course the changelog should also note explicitly that this is a fork of Xen 4.14 in all the released versions that have patches from Xen upstream 4.16. Perhaps there is a way to also indicate this in the version name and number of the packages, but I do not know if there are conventions or policies to handle a version change that is really the start of a fork. If so, we should follow them.