Dont mangle key typos.

[aaroncrespo]

Carthage/Carthage#1926

I think for the sake of better error messages Commandant should not try and convert flags to a set

Commandant/Sources/Commandant/ArgumentParser.swift

Line 75 in 903eaec

return .flag(Set(opt))

It will mangle a --key typo and produce confusing errors.

If flags are passed as used ex:

$ carthage update -platform
Unrecognized arguments: -armpfolt

Should become

$ carthage update -platform
Unrecognized arguments: -platform

[mdiep]

That's only done if there's a single -, which denotes a single-letter flag/argument. That's how basically all *nix tools work.

[aaroncrespo]

do all nix tools randomly reorder the input in the error message?

[aaroncrespo]

This issue isn't about the fact that there is an error message. this issue is about the formatting and content of the error message.

[mdiep]

It looks like most tools bail on the first unknown option:

$ python -asenxtaboe 
Unknown option: -a

I'm not sure if that's better as it gives you less information.