--- a/mercurial/repoview.py	Tue Nov 05 14:31:50 2019 -0800
+++ b/mercurial/repoview.py	Tue Nov 05 14:33:02 2019 -0800
@@ -325,6 +325,12 @@
                 raise error.FilteredIndexError(rev)
             return super(filteredchangelog, self).parentrevs(rev)
 
+        def flags(self, rev):
+            """filtered version of revlog.flags"""
+            if rev in self.filteredrevs:
+                raise error.FilteredIndexError(rev)
+            return super(filteredchangelog, self).flags(rev)
+
     cl.__class__ = filteredchangelog
 
     return cl