diff --git a/hgext/remotefilelog/remotefilelog.py b/hgext/remotefilelog/remotefilelog.py
--- a/hgext/remotefilelog/remotefilelog.py
+++ b/hgext/remotefilelog/remotefilelog.py
@@ -48,7 +48,7 @@
             raise KeyError(node)
         return node
 
-class remotefilelog(flagutil.flagprocessorsmixin):
+class remotefilelog(object):
 
     _generaldelta = True
     _flagserrorclass = error.RevlogError
diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -261,7 +261,7 @@
             p = versionformat_pack(version) + p[4:]
         return p
 
-class revlog(flagutil.flagprocessorsmixin):
+class revlog(object):
     """
     the underlying revision storage object
 
diff --git a/mercurial/revlogutils/flagutil.py b/mercurial/revlogutils/flagutil.py
--- a/mercurial/revlogutils/flagutil.py
+++ b/mercurial/revlogutils/flagutil.py
@@ -79,14 +79,6 @@
         raise error.Abort(msg)
     flagprocessors[flag] = processor
 
-class flagprocessorsmixin(object):
-    """basic mixin to support revlog flag processing
-
-    Make sure the `_flagprocessors` attribute is set at ``__init__`` time.
-
-    See the documentation of the ``_processflags`` method for details.
-    """
-
 def processflagswrite(revlog, text, flags, sidedata):
     """Inspect revision data flags and applies write transformations defined
     by registered flag processors.
diff --git a/tests/simplestorerepo.py b/tests/simplestorerepo.py
--- a/tests/simplestorerepo.py
+++ b/tests/simplestorerepo.py
@@ -91,7 +91,7 @@
     node = attr.ib(default=None)
 
 @interfaceutil.implementer(repository.ifilestorage)
-class filestorage(flagutil.flagprocessorsmixin):
+class filestorage(object):
     """Implements storage for a tracked path.
 
     Data is stored in the VFS in a directory corresponding to the tracked