fix(cabal-install): Include all libraries in the --haddock-for-hackage docs tarball

[zlonast]

Fix: #12364

Fix a bug where cabal haddock --haddock-for-hackage created a <pkgid>-docs.tar.gz containing the haddocks of only one library of the package (e.g. only an internal library, or only the main library).

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[ulysses4ever]

This looks promising, thank you. Any chance you could actually try to upload a package candidate from a tar created this way?

[ulysses4ever]

Can’t you tar before copying back from tmp? And just copy the tar. Copying directories is slower.

[zlonast]

I couldn't upload (no Hackage credentials), but I check hackage-server locally.

hackage-server requires tar ^>= 0.7
cabal requires tar >= 0.5.0.3 && < 0.8

[zlonast]

Perhaps we should raise the lower limit?