sFTP integration test failures

[meejah]

On a new PR, I'm seeing some sFTP failures.

Presumably, this means some updated library is causing problems. Example of the failure: ​https://github.com/tahoe-lafs/tahoe-lafs/runs/4731647245

[itamarst]

Looks like this might be a bug in Paramiko 2.9.0, and fixed in Paramiko 2.9.1. In which case retrying the builds should fix it.

[itamarst]

Ah, no, that was related but different bug. The likely cause is ​https://github.com/paramiko/paramiko/issues/1961 which is still present in latest Paramiko 2.9.1. So next will try pinning older version.

[meejah]

A workaround is now merged .. I _guess_ it might make sense to leave this open as a reminder to undo the pin if things are fixed upstream? (Or just close, since the immediate problem -- integration-test failures -- is gone...)

[exarkun]

For reference, the fix landed via ​https://github.com/tahoe-lafs/tahoe-lafs/pull/1169 in ​https://github.com/tahoe-lafs/tahoe-lafs/commit/4cdbf7fb0cb1a462f4edf6ed93a74dc6f4df0499

To the question of whether this ticket should be open or closed: one ticket, one PR.

As you say, the problem is solved: the SFTP integration tests no longer fail because of this Paramiko regression. I don't even know that removing the pin is sensible after Paramiko fixes the issue. The most obvious thing that does is open us up to future regressions.

Maybe we want to revisit the pin in a month or a year or something and move it to a newer version if there is some interesting reason to do so. The same probably applies to all of our dependencies. Do we want to track that work with a ticket or some other way? A ticket sounds kind of nice but I'm not convinced it would actually remind anyone to do anything in, say, six months. More likely it will just get lost in the pile.