ng command --help results in undefined

[delight]

Please provide us with the following information:
OS?

Windows 7, 8 or 10. Linux (which distribution). Mac OSX (Yosemite? El Capitan?)
Ubuntu 14.04.5 LTS

Versions.

Please run ng --version. If there's nothing outputted, please run in a Terminal: node --version and paste the result here:
@angular/cli: 1.0.0-beta.31
node: 6.9.5
os: linux x64

Repro steps.

Was this an app that wasn't created using the CLI? What change did you do on your code? etc.
The log given by the failure.

Normally this include a stack trace and some more information.

ng serve --help (or any other command ng new --help etc.) result in undefined

ng build --help
undefined

Mention any other details that might be useful.

ng help is still working only ng command --help stopped working

[delight]

duplicate of #4595

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