Build cabal before help output

[philderbeast]

Fixes #12375. I cherry picked the fix from #12359 by @zlonast and tested it on #11778.

---

• Patches conform to the coding conventions.
• Is this a PR that fixes CI? If so, it will need to be backported to older cabal release branches (ask maintainers for directions).

[philderbeast]

Bumping to high priority as #12300 is failing CI without this fix.

[ulysses4ever]

TIL | in make...

[Mikolaj]

This doesn't affect 3.18, right?

[philderbeast]

This doesn't affect 3.18, right?

The 3.18 branch doesn't have the .github/workflows/cmd-help.yml workflow so it is unaffected and doesn't need a backport.

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-09-25 17:24 UTC · Rule: default · triggered by rule Put pull requests in the rebase+merge queue
• ✅ Checks skipped · PR is already up-to-date
• ✅ Merged — 2026-09-25 17:35 UTC · at 773c039647e98146e4c75a318123fe079abb9c06 · merge

This pull request spent 10 minutes 40 seconds in the queue, including 1 second running CI.

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