diff -r dee73a97e132 -r b7de186efd82 mercurial/commandserver.py
--- a/mercurial/commandserver.py	Tue Oct 16 08:29:24 2018 +0200
+++ b/mercurial/commandserver.py	Tue Oct 16 08:41:58 2018 +0200
@@ -369,7 +369,7 @@
             cerr = sv.cerr
         else:
             cerr = channeledoutput(fout, 'e')
-        traceback.print_exc(file=cerr)
+        cerr.write(encoding.strtolocal(traceback.format_exc()))
         raise
     finally:
         fin.close()