diff -r 55d132525155 -r 642e31cb55f0 mercurial/branchmap.py
--- a/mercurial/branchmap.py	Mon Feb 21 13:03:43 2022 -0700
+++ b/mercurial/branchmap.py	Mon Feb 21 13:08:28 2022 -0700
@@ -62,7 +62,7 @@
 unpack_from = struct.unpack_from
 
 
-class BranchMapCache(object):
+class BranchMapCache:
     """mapping of filtered views of repo with their branchcache"""
 
     def __init__(self):
@@ -169,7 +169,7 @@
         return b'branch cache'
 
 
-class branchcache(object):
+class branchcache:
     """A dict like object that hold branches heads cache.
 
     This cache is used to avoid costly computations to determine all the
@@ -631,7 +631,7 @@
 _rbccloseflag = 0x80000000
 
 
-class revbranchcache(object):
+class revbranchcache:
     """Persistent cache, mapping from revision number to branch name and close.
     This is a low level cache, independent of filtering.