[PATCH 2 of 2 STABLE] commandserver: get around ETIMEDOUT raised by selectors2

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1543841115 -32400
#      Mon Dec 03 21:45:15 2018 +0900
# Branch stable
# Node ID 35a596a6b8fa1cb71271d6d4681b0ff7883ea25c
# Parent  d1bda397df7330fb192a94dcb0801928a2492074
commandserver: get around ETIMEDOUT raised by selectors2

selector.select() should exits with an empty event list on timed out, but
selectors2 raises OSError if timeout expires while recovering from EINTR.

Spotted while debugging new chg feature.

diff --git a/mercurial/commandserver.py b/mercurial/commandserver.py
--- a/mercurial/commandserver.py
+++ b/mercurial/commandserver.py
@@ -472,7 +472,15 @@ class unixforkingservice(object):
                 # waiting for recv() will receive ECONNRESET.
                 self._unlinksocket()
                 exiting = True
-            ready = selector.select(timeout=h.pollinterval)
+            try:
+                ready = selector.select(timeout=h.pollinterval)
+            except OSError as inst:
+                # selectors2 raises ETIMEDOUT if timeout exceeded while
+                # handling signal interrupt. That's probably wrong, but
+                # we can easily get around it.
+                if inst.errno != errno.ETIMEDOUT:
+                    raise
+                ready = []
             if not ready:
                 # only exit if we completed all queued requests
                 if exiting: