diff -r dff95420480f -r 01304095256c mercurial/revlog.py
--- a/mercurial/revlog.py	Sat Sep 07 00:16:32 2019 +0200
+++ b/mercurial/revlog.py	Sat Sep 07 00:22:38 2019 +0200
@@ -1601,6 +1601,17 @@
         return mdiff.textdiff(self.rawdata(rev1),
                               self.rawdata(rev2))
 
+    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, flagutil.processflagsraw(self, text, flags)
+        elif operation == 'read':
+            return flagutil.processflagsread(self, text, flags)
+        else: # write operation
+            return flagutil.processflagswrite(self, text, flags)
+
     def revision(self, nodeorrev, _df=None, raw=False):
         """return an uncompressed revision of a given node or revision
         number.