System test for #9096 (truncated stdout)

[edsantiago]

This actually tests conmon, not podman; but that's the whole
point of system tests in the first place: if a problem exists,
we want to fail loudly, no matter whose fault it is.

(I can't get this to fail on my f33 laptop; OP on #9096 claims
it only fails on Ubuntu. We'll see what happens in CI).

Signed-off-by: Ed Santiago [email protected]

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[edsantiago]

@giuseppe @haircommander could you take a quick look and LMK if my test logic here is meaningful? Does the podman log output path exercise a close-enough code path to that of plain stdout?

[vrothberg]

Very clever to use a log file 👍

[haircommander]

I've pulled this in to #8979 where I'm seeing failures from conmon 2.0.25. Hopefully this fails there, and updating to conmon 2.0.26 will fix it, verifying this issue is fixed

[rhatdan]

/lgtm

[edsantiago]

@haircommander thank you! Although this PR has just merged, could you please follow up with your findings? (Right now I see #8979 stuck in all-red in int tests, which means the sys tests didn't get a chance to run)