stable ordering of test output

[Matt Harbison]

On Fri, 03 Mar 2017 17:45:56 -0500, Danek Duvall <danek.duvall at oracle.com>  
wrote:

> I frequently get failures like this:
>
>     --- .../mercurial.hg/tests/test-bundle2-exchange.t
>     +++ .../mercurial.hg/tests/test-bundle2-exchange.t.err
>     @@ -1042,11 +1042,11 @@
>        $ hg --config devel.legacy.exchange=bundle1 clone  
> ssh://user@dummy/bundle2onlyserver not-bundle2-ssh
>        requesting all changes
>        adding changesets
>     -  remote: abort: incompatible Mercurial client; bundle2 required
>     -  remote: (see  
> https://www.mercurial-scm.org/wiki/IncompatibleClient)
>        transaction abort!
>        rollback completed
>        abort: stream ended unexpectedly (got 0 bytes, expected 4)
>     +  remote: abort: incompatible Mercurial client; bundle2 required
>     +  remote: (see  
> https://www.mercurial-scm.org/wiki/IncompatibleClient)
>        [255]
>       $ cat > bundle2onlyserver/.hg/hgrc << EOF
>
>     ERROR: test-bundle2-exchange.t output changed
>
> It's usually fairly consistent, at least for a period of time, and then  
> it
> goes away.  Presumably it's some sort of fairly stable timing issue, and
> possibly unique to the environment I'm running in (at least, I assume  
> that
> the official tests aren't showing this).

The symptoms seem similar to what was happening on Windows a few years ago.

https://www.mercurial-scm.org/repo/hg/rev/83f6c4733ecc
https://www.mercurial-scm.org/repo/hg/rev/2abbf4750915

The commit referenced in the first link's message might also be of  
interest.

> I could patch the tests locally to reorder the lines, but if it's really  
> an
> environmental issue, then that's guaranteed to work consistently even for
> me.
>
> Is this (ever? frequently?) an issue for anyone else?
>
> I can't think of any particularly satisfying solution to this, other than
> perhaps separating the remote lines from the local lines, and comparing
> each of those independently.  Would that make sense?
>
> Thanks,
> Danek
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