diff -r 037890ecaff5 -r 55886050a583 mercurial/chgserver.py
--- a/mercurial/chgserver.py	Thu Feb 02 17:19:26 2023 +0100
+++ b/mercurial/chgserver.py	Thu Feb 02 17:19:35 2023 +0100
@@ -236,7 +236,7 @@
             # will behave differently (i.e. write to stdout).
             if (
                 out is not self.fout
-                or not util.safehasattr(self.fout, b'fileno')
+                or not util.safehasattr(self.fout, 'fileno')
                 or self.fout.fileno() != procutil.stdout.fileno()
                 or self._finoutredirected
             ):