Pulled out of #16803 since the drive-by cleanup was maybe not as
drive-by as I had hoped.
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Base: `develop` <!-- git-stack-base-branch:develop -->
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Original commit schedule, with full messages:
<ol>
<li>
Add a --generate-only option
</li>
</ol>
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Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>
