diff -r cf415777a22c -r c8b9943c07eb mercurial/chgserver.py
--- a/mercurial/chgserver.py	Mon May 08 15:31:34 2017 -0700
+++ b/mercurial/chgserver.py	Sun Apr 30 11:08:27 2017 -0700
@@ -44,6 +44,7 @@
 import inspect
 import os
 import re
+import socket
 import struct
 import time
 
@@ -516,6 +517,7 @@
         tempaddress = _tempaddress(self._realaddress)
         util.bindunixsocket(sock, tempaddress)
         self._socketstat = os.stat(tempaddress)
+        sock.listen(socket.SOMAXCONN)
         # rename will replace the old socket file if exists atomically. the
         # old server will detect ownership change and exit.
         util.rename(tempaddress, self._realaddress)