hostname: fix -d flag

[bakanovskii]

Fixes #8656

[AnarchistHoneybun]

you could change the text to say "Fixes ..." or "Resolves ..." to automatically link the pr to the issue

[sylvestre]

could you please add a test to make sure we don't regress ? thanks

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/misc/stdbuf (fails in this run but passes in the 'main' branch)

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/misc/stdbuf (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/misc/tee (passes in this run but fails in the 'main' branch)

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/misc/stdbuf (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/misc/tee (passes in this run but fails in the 'main' branch)

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/misc/stdbuf (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/misc/tee (passes in this run but fails in the 'main' branch)

[bakanovskii]

could you please add a test to make sure we don't regress ? thanks

sure! I also found https://github.com/uutils/hostname/tree/main this repo which seems to be more complete
Is this a stage repo (WIP)? Should I contribute further to hostname binary?

[bakanovskii]

@sylvestre, hello! Could you please review again?