RegistryOption does not show possible values with value_switches=False

[Alexander Belchenko]

Adeodato Simó пишет:
> I just noticed that if I create a RegistryOption with value_switches=False, 
> the help output for the command does not include a list of possible values
> for the option. Is this intentional? How can the user know those values?
> Or is it believed that every RegistryOption in the bzr codebase should be
> using value_switches=True?

I'm also encounter this. IMO, it's the bug.