Support commands which throw error on -- argument

[avaly]

Using certain tools (e.g. Flow v0.48.0: flow focus-check) will not run correctly if they don't understand/expect an argument --.

Steps to reproduce

1. git init
2. npm init -y
3. yarn add lint-staged flow-bin@0.48.0
4. flow init
5. .lintstagedrc:

   {
     "*.js": ["flow focus-check"]
   }

6. index.js:

   // @flow

7. git add .
8. lint-staged

Actual result
The flow focus-check command will fail via lint-staged

Expected result
The flow focus-check command should pass, like it does when being run externally like: flow focus-check index.js

[avaly]

FYI: flow focus-check only supports one single file as an argument, so using it with lint-staged is currently not possible since it will throw error when more than one file is staged.

Hoping this gets addressed in facebook/flow#4189

However this should still be fixed in lint-staged.

[gabrielhpugliese]

Did that last PR fix this issue? It doesn't seem so to me. I still experience problems with flow :)