diff -r 119790e1c67c -r 223b47235d1c mercurial/interfaces/repository.py
--- a/mercurial/interfaces/repository.py	Sat Apr 10 11:27:40 2021 +0200
+++ b/mercurial/interfaces/repository.py	Thu Apr 08 16:55:17 2021 +0200
@@ -1856,7 +1856,7 @@
     def savecommitmessage(text):
         pass
 
-    def register_sidedata_computer(kind, category, keys, computer):
+    def register_sidedata_computer(kind, category, keys, computer, flags):
         pass
 
     def register_wanted_sidedata(category):