repo-config: adjust "root" path for parsing shared config That "root" argument is used to resolve relative path in the config. For a repository config it is expected to be the root of the working copy (the directory that contains the `.hg` directory). Before this patch, the config was loaded using the `.hg/` directory of the share source, this is not the right directory and would break in all cases. Instead we use the working copy directory of the share. This is not always good, if some relative path we pointing inside the source's `.hg`. However that is better than something plain wrong. Also this is the right answer for all path that refer to the actual working copy. Fixing this ambiguity is left as an exercises to a future developer. At least we no longer use a plain invalid value.