diff -r 55d132525155 -r 642e31cb55f0 mercurial/utils/compression.py
--- a/mercurial/utils/compression.py	Mon Feb 21 13:03:43 2022 -0700
+++ b/mercurial/utils/compression.py	Mon Feb 21 13:08:28 2022 -0700
@@ -32,7 +32,7 @@
 )
 
 
-class propertycache(object):
+class propertycache:
     def __init__(self, func):
         self.func = func
         self.name = func.__name__
@@ -47,7 +47,7 @@
         obj.__dict__[self.name] = value
 
 
-class compressormanager(object):
+class compressormanager:
     """Holds registrations of various compression engines.
 
     This class essentially abstracts the differences between compression
@@ -219,7 +219,7 @@
 compengines = compressormanager()
 
 
-class compressionengine(object):
+class compressionengine:
     """Base class for compression engines.
 
     Compression engines must implement the interface defined by this class.
@@ -338,7 +338,7 @@
         raise NotImplementedError()
 
 
-class _CompressedStreamReader(object):
+class _CompressedStreamReader:
     def __init__(self, fh):
         if safehasattr(fh, 'unbufferedread'):
             self._reader = fh.unbufferedread
@@ -482,7 +482,7 @@
     def decompressorreader(self, fh):
         return _GzipCompressedStreamReader(fh)
 
-    class zlibrevlogcompressor(object):
+    class zlibrevlogcompressor:
         def __init__(self, level=None):
             self._level = level
 
@@ -626,7 +626,7 @@
     def decompressorreader(self, fh):
         return fh
 
-    class nooprevlogcompressor(object):
+    class nooprevlogcompressor:
         def compress(self, data):
             return None
 
@@ -698,7 +698,7 @@
     def decompressorreader(self, fh):
         return _ZstdCompressedStreamReader(fh, self._module)
 
-    class zstdrevlogcompressor(object):
+    class zstdrevlogcompressor:
         def __init__(self, zstd, level=3):
             # TODO consider omitting frame magic to save 4 bytes.
             # This writes content sizes into the frame header. That is
@@ -782,7 +782,7 @@
 
     # We need to format the docstring. So use a dummy object/type to hold it
     # rather than mutating the original.
-    class docobject(object):
+    class docobject:
         pass
 
     for name in compengines: