diff -r 38c62272f462 -r 519b45603880 mercurial/revlogutils/flagutil.py
--- a/mercurial/revlogutils/flagutil.py	Mon Sep 02 17:06:15 2019 +0200
+++ b/mercurial/revlogutils/flagutil.py	Sat Sep 07 10:06:32 2019 -0700
@@ -91,6 +91,8 @@
 
     def _processflags(self, text, flags, operation, raw=False):
         """deprecated entry point to access flag processors"""
+        msg = ('_processflag(...) use the specialized variant')
+        util.nouideprecwarn(msg, '5.2', stacklevel=2)
         if raw:
             return text, self._processflagsraw(text, flags)
         elif operation == 'read':