diff -r 06440ba06bc0 -r 7548522742b5 mercurial/localrepo.py
--- a/mercurial/localrepo.py	Sun Mar 12 12:54:11 2017 -0700
+++ b/mercurial/localrepo.py	Fri Aug 05 14:09:04 2016 +0200
@@ -932,6 +932,7 @@
         return None
 
     def join(self, f, *insidef):
+        self.ui.deprecwarn("use 'repo.vfs.join' instead of 'repo.join'", '4.0')
         return self.vfs.join(os.path.join(f, *insidef))
 
     def wjoin(self, f, *insidef):