vfs: use 'vfs' module directly in 'hgext.mq'

Now that the 'vfs' classes moved in their own module, lets use the new module
directly. We update code iteratively to help with possible bisect needs in the
future.

hgext/mq.py

@@ -94,6 +94,7 b' from mercurial import ('
     smartset,
     subrepo,
     util,
+    vfs as vfsmod,
 )
 
 release = lockmod.release
@@ -434,7 +435,7 b' class queue(object):'
         except IOError:
             curpath = os.path.join(path, 'patches')
         self.path = patchdir or curpath
-        self.opener = scmutil.vfs(self.path)
+        self.opener = vfsmod.vfs(self.path)
         self.ui = ui
         self.baseui = baseui
         self.applieddirty = False