localrepo: use "self.wvfs.join()" instead of "os.path.join()"

As a part of migration to vfs, this patch uses "self.wvfs.join()"
instead of "os.path.join()", while initialization of fields in the
constructor of "localrepository" class.

mercurial/localrepo.py

@@ -40,7 +40,7 b' class localrepository(repo.repository):'
         self.wopener = scmutil.opener(path, expand=True)
         self.wvfs = self.wopener
         self.root = self.wvfs.base
-        self.path = os.path.join(self.root, ".hg")
+        self.path = self.wvfs.join(".hg")
         self.origroot = path
         self.auditor = scmutil.pathauditor(self.root, self._checknested)
         self.opener = scmutil.opener(self.path)