check/test/update claim about compatibility with old clients and servers in relnotes.txt

[davidsarah]

From ticket:541#comment:9 :

relnotes.txt says:

Servers from this release can serve clients of all versions back to v1.0 and clients from this release can use servers of all versions back to v1.0.

which I believe is already incorrect, although I can't remember why not. Should we be making this claim when we don't test it?

[marlowe]

A couple of questions as we come up to 1.10.

1) Do we wish to test compatibility and if so, how far back?
2) If we don't desire to test this, do we want to simply remove the statement all together or add a "should" into the statement?

[ClashTheBunny]

We don't anymore. It used to be done. Here's zooko's statement on this:

It would be cool for someone to set up to run inter-node regression tests of various versions.

Yes, that would! I value backward-compatibility, because I recognize that people are often more conservative about storage than about other kinds of software.

There used to be a thing called Memory Lane:

​https://tahoe-lafs.org/trac/tahoe-lafs/wiki/TestGrid?version=54

But it needs a maintainer:

​https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1002# do some renovations on Memory Lane

That would be a pretty cool thing to have on the live Test Grid, so if you had a question like "What happens if you upload a new XSalsa20-encrypted file using Tahoe-LAFS v14.1 to a grid with one Tahoe-LAFS storage server of each version going back a few years: 1.10.0, 1.9.2, 1.8.3, 1.7.1, 1.6.1, 1.5, 1.4.1, 1.3, 1.2, 1.1, and 1.0, what happens?", then you can just try it and see! (Hopefully the answer is It Just Works because the storage servers don't know what kind of encryption you are using on the client side. ☺)

[marlowe]

Okay, I will make the appropriate change to the documentation and submit a patch tonight.

[zooko]

to close this, we need only a minor patch to the docs. Brian is taking over this for the 1.10 release.

[Brian Warner <warner@…>]

In a216145a2e9be4b0:

relnotes: soften compatibility claims until we have test infrastructure for them

Closes #1773