mercurial/changelog.py

--- a/mercurial/changelog.py	Mon Sep 21 15:05:38 2020 -0400
+++ b/mercurial/changelog.py	Wed Sep 16 12:13:46 2020 -0700
@@ -403,9 +403,21 @@
         self._delayed = False
         self._delaybuf = None
         self._divert = False
-        self.filteredrevs = frozenset()
+        self._filteredrevs = frozenset()
+        self._filteredrevs_hashcache = {}
         self._copiesstorage = opener.options.get(b'copies-storage')
 
+    @property
+    def filteredrevs(self):
+        return self._filteredrevs
+
+    @filteredrevs.setter
+    def filteredrevs(self, val):
+        # Ensure all updates go through this function
+        assert isinstance(val, frozenset)
+        self._filteredrevs = val
+        self._filteredrevs_hashcache = {}
+
     def delayupdate(self, tr):
         """delay visibility of index updates to other readers"""