phase: handle phase with no command flag Before this changeset, all existing phases have a corresponding flag on the `hg phase` command. (eg: `hg phase --draft`). After this changeset, a phase can exists without having an associated flag. This is useful to introduce a new internal phase that we do not want to expose to user.

phase: explicitly exclude secret phase and above The comment explicitly mention the secret phase so we should as well use that in the code.