nice: add newline to warning message

[Devel08]

This pr closes #12927. Is test required? I don't think that can regress in future

[oech3]

Is test required?

We can change existing tests to use .stdout_is() after stripping errno instead.

[Devel08]

Ahh, it succeeds with stderr, alright ... Ready for review

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/cut/bounded-memory (passes in this run but fails in the 'main' branch)

[Devel08]

@cakebaker it seems that there is already test_negative_adjustment, should I remove my test_nice_adj_negative and edit test_negative_adjustment to use stdout_is with newline?

[cakebaker]

I would "merge" the two tests into one: keep your code as it is cleaner and take the comment from the other test.

[sylvestre]

needs to be rebase
and please move the tests where it was in the file

[codspeed-hq]

Merging this PR will improve performance by 3.12%

⚡ 1 improved benchmark
✅ 322 untouched benchmarks
⏩ 46 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	du_all_wide_tree[(5000, 500)]	16.7 ms	16.2 ms	+3.12%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing Devel08:fix-issue-12927 (0d3541f) with main (de30f0a)}

Footnotes

1. 46 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[cakebaker]

Thanks!