clone: allow local cloning to create more than one level of directories I figure cloning a remote repository is more common, thus it's more likely that some people might be relying on the less restrictive behavior. Additionally, `hg init` will also create more than one level of missing directories. I also have a use case for reading the subrepos from .hgsub, and sharing them into the normal nested location on the server. SCM Manager doesn't host subrepos in the normal nested location, which is nice for deduplicating the repository data, but confuses `hg verify`. Some of the subrepos are in the root of the repositories, while others are one or two directories deep. So not having to build up the parent path first is desirable.