poetry complains about missing argument when using `--help`

[finswimmer]

• [x] I am on the latest Poetry version.
• [x] I have searched the issues of this repo and believe that this is not a duplicate.
• [ ] If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

Issue

I don't know whether this is a poetry issue or cleo and if this problem arises in earlier versions.

When I type poetry add --help I receive the error message

Not enough arguments (missing: "name").

Similar for poetry remove --help

Not enough arguments (missing: "packages").

If I append any name I get the help page.

The expected behavior would be, that whenever I use --help, the help page should be displayed and mandatory arguments for sub command shouldn't be checked.

Saw this with version 1.0.0b6 and 1.0.0b7

[kawing-chiu]

Same issue here at 1.0.0b7 :)

But poetry help add will correctly show the help page.

[mrezzamoradi]

poetry <command> --help does not work for the following commands:

• add
• remove
• search
• run
• new

poetry version: 1.0.0
OS: Ubuntu 18.04.2 LTS