--override-input as EXTRA_NIX_ARGS is broken

[shivaraj-bh]

I have added a test in 65bbe90, which is expected to pass. But fails with:

> cargo test -p omnix-cli command::ci::test_haskell_multi_nix_override_input
...
test command::ci::test_haskell_multi_nix_override_input ... FAILED

failures:

---- command::ci::test_haskell_multi_nix_override_input stdout ----
Error: Failed to run `om ci run`:

👟 Reading om.ci config from flake
❄️  nix --override-input haskell-flake github:srid/haskell-flake/c8622c8a259e18e0a1919462ce885380108a723c build '/nix/store/j252k66dnma68pygfqhk8pwacdyykcyh-nix-rs-flake-metadata#default' -L --print-out-paths --no-link --override-input flake github:srid/haskell-multi-nix/c85563721c388629fa9e538a1d97274861bc8321 --override-input include-inputs /nix/store/wb47j3cp8fjjgidlqlr2mhwi5zwmvsqh-source️
error: unrecognised flag '--override-input'
Try 'nix --help' for more information.
Error: Flake function error: `nix build` failed; exit code: Some(1)

Caused by:
    `nix build` failed; exit code: Some(1)

The test passes in 187547c but fails starting from 5485408

[shivaraj-bh]

semantically it makes sense to not treat --override-input as EXTRA_NIX_ARGS as it is extra args for some subcommands of nix. But since there was a change in behaviour, I was wondering what could be the alternative way to pass --override-input to only subcommands that supports it? (Without an alternative, CI workflows internally at Juspay will break)

[srid]

The particular problem in this case is to do with position of the argument, not its kind itself. --override-input should appear after the subcommand, build, and not before that. Nix's CLI parser is rather retarded 🤷🏾

❯ cargo run -p omnix-cli -- ci run github:srid/haskell-template -- --override-input flake-parts github:hercules-ci/flake-parts
[..]
👟 Reading om.ci config from flake
❄️  nix --override-input flake-parts github:hercules-ci/flake-parts build '/nix/store/f9l6vrwrwnfba76cy5vrw64rb19rwfsx-nix-rs-flake-metadata#default' -L --print-out-paths --no-link --override-input flake github:srid/haskell-template --override-input include-inputs /nix/store/wb47j3cp8fjjgidlqlr2mhwi5zwmvsqh-source️
error: unrecognised flag '--override-input'

[srid]

only subcommands that supports it

More generally: #440