largefiles: delegate to the wrapped clone command This allows the wrapped command's validation code to run (which is currently only to ensure 'noupdate' and 'updaterev' aren't both specified), the copy/pasted unpacking of hg.clone() args to be removed, and any future changes to the base command (however unlikely) to be inherited by largefiles. Unfortunately, the command override can't be swapped entirely for an hg.clone() override because the extra --all-largefiles arg needs to be injected. It also isn't enough to call the wrapped clone command and leave the caching code after it, because the file caching code needs access to the destination repo, which is only available from hg.clone(). An alternative would be to use the dest path in the clone command override to re-obtain a reference to the repo. A slight deviation from the regular hg.clone() function is that the repo is NOT deleted if the caching fails, but that was also the previous behavior. Maybe it should for consistency?