localrepo: use file API via vfs while ensuring repository directory

As a part of migration to vfs, this patch invokes some file API
indirectly via vfs, while ensuring repository directory in the
constructor of "localrepository" class.

New file API are added to "scmutil.abstractopener" class, because they
are also used via other derived classes than "scmutil.opener".

But "join()" is not yet defined other than "scmutil.opener" class,
because it should not be used via other opener classes yet.

mercurial/localrepo.py

@@ -58,14 +58,14 b' class localrepository(repo.repository):'
         except IOError:
             pass
 
-        if not os.path.isdir(self.path):
+        if not self.vfs.isdir():
             if create:
-                if not os.path.exists(self.root):
-                    util.makedirs(self.root)
-                util.makedir(self.path, notindexed=True)
+                if not self.wvfs.exists():
+                    self.wvfs.makedirs()
+                self.vfs.makedir(notindexed=True)
                 requirements = self._baserequirements(create)
                 if self.ui.configbool('format', 'usestore', True):
-                    os.mkdir(os.path.join(self.path, "store"))
+                    self.vfs.mkdir("store")
                     requirements.append("store")
                     if self.ui.configbool('format', 'usefncache', True):
                         requirements.append("fncache")

mercurial/scmutil.py

@@ -190,6 +190,21 b' class abstractopener(object):'
         finally:
             fp.close()
 
+    def mkdir(self, path=None):
+        return os.mkdir(self.join(path))
+
+    def exists(self, path=None):
+        return os.path.exists(self.join(path))
+
+    def isdir(self, path=None):
+        return os.path.isdir(self.join(path))
+
+    def makedir(self, path=None, notindexed=True):
+        return util.makedir(self.join(path), notindexed)
+
+    def makedirs(self, path=None, mode=None):
+        return util.makedirs(self.join(path), mode)
+
 class opener(abstractopener):
     '''Open files relative to a base directory
 
@@ -293,7 +308,10 b' class opener(abstractopener):'
         self.auditor(path)
 
     def join(self, path):
-        return os.path.join(self.base, path)
+        if path:
+            return os.path.join(self.base, path)
+        else:
+            return self.base
 
 class filteropener(abstractopener):
     '''Wrapper opener for filtering filenames with a function.'''