`cabal upload` could by default do a `sdist` and upload the thus generated tar

[andreasabel]

When I do cabal upload, I get

cabal: the 'upload' command expects at least one .tar.gz archive.

If no archive is given on the command line, it could first do an sdist and then upload the thus generated tar.gz.

My workaround is the following cabal-upload shell script:

cabal sdist | tail -1 | xargs cabal upload "$@"
cabal haddock --haddock-for-hackage | tail -1 | xargs cabal upload -d "$@"

[jneira]

makes sense to me, related #3837 and #5064