diff -r d9fc51f77cc5 -r d1bda397df73 mercurial/thirdparty/selectors2.py
--- a/mercurial/thirdparty/selectors2.py	Wed Nov 14 10:12:43 2018 -0500
+++ b/mercurial/thirdparty/selectors2.py	Mon Dec 03 21:31:19 2018 +0900
@@ -708,7 +708,7 @@
                     if expires is not None:
                         current_time = monotonic()
                         if current_time > expires:
-                            raise OSError(errno=errno.ETIMEDOUT)
+                            raise OSError(errno.ETIMEDOUT, 'Connection timed out')
                         if recalc_timeout:
                             if "timeout" in kwargs:
                                 kwargs["timeout"] = expires - current_time