py3: replace "%r" by"'%s'% for py3-compatible (and clearer) quoting in chg

Differential Revision: https://phab.mercurial-scm.org/D7375

mercurial/chgserver.py

@@ -505,7 +505,7 b' class chgcmdserver(commandserver.server)'
         path = self._readstr()
         if not path:
             return
-        self.ui.log(b'chgserver', b'chdir to %r\n', path)
+        self.ui.log(b'chgserver', b"chdir to '%s'\n", path)
         os.chdir(path)
 
     def setumask(self):