Thanks!

@GrahamcOfBorg build nixosTests.matrix-synapse

About the backport to 19.03, I'm not sure we should actually continue backporting all the updates. Now that the matrix protocol has stabilized, I'm starting to think we should backport only on security fixes (ideally only security fixes, but it requires more time…), like we do for other packages, as we no longer have the “synapse will just break if not updated” deadline. (disclaimer: I haven't checked the Changelog yet for security fixes, but there was nothing obvious)

cc @Ralith @roblabla @pacien for your opinion on this matter.

I agree, we can continue jumping some version that don't include a security issues.
That means 0.99.4 would not go into 19.03 but 0.99.4.1 might need to be backported, thus jumping 0.99.4.

we should backport only on security fixes

Basically every matrix-synapse release comes with a bunch of bugfixes. Is that not enough reason to backport (as long as it is not a major version change)?

@fadenb A bugfix is not necessarily a good thing to backport, as a bugfix can potentially break a user's workflow. This is for instance how debian handles stability (backport only the patches that fix security issues). On the other hand, the only current source of documentation for nixpkgs' backports (though it wasn't written with this aim, so this list was not actually the topic of the RFC) states that “patch-level and minor-level updates” should be backported. Whether 0.99.3.2 -> 0.99.4 is a minor update is an open question -- semver states that 0.x versions are all assumed to be incompatible. Also, basing our decisions on just version numbers would be plain wrong, given that projects don't all use semver.

All that to say, the policy around backports and what is acceptable breakage is currently quite fuzzy. If you feel like writing an RFC to clarify the situation, it would most likely help! Such an RFC would make clear what the acceptable level of breakage is, and which kinds of bugfixes should be backported (all security fixes, fixes when the program doesn't run at all… cosmetic fixes? also, how to handle the cases when we don't have enough manpower to manually extract just the wanted fixes, and will just bump the version).

For now, until someone comes up with a concrete “my synapse breaks and wouldn't with this update” case (or if there's a security fix), I don't feel comfortable backporting this commit :)