[PATCH] dispatch: treat SIGPIPE as a termination signal (BC)

[Simon Farnsworth]

# HG changeset patch
# User Simon Farnsworth <simonfar at fb.com>
# Date 1486498104 28800
#      Tue Feb 07 12:08:24 2017 -0800
# Node ID e1150763706818fffa62c81a72a88574d20caea1
# Parent  1f51b4658f21bbb797e922d155c1046eddccf91d
dispatch: treat SIGPIPE as a termination signal (BC)

pager previously set SIGPIPE to immediately exit the process, ignoring any
Python @atexit handlers, exception handling etc - just instant termination.

Simply removing this as per changeset aaa751585325 meant that when you
aborted a long running pager command, Mercurial would not quit; instead, we
should add SIGPIPE to the list of termination signals in dispatch.py.

This is a slight BC break, as previously, a process that was piping data
into or out of Mercurial would not kill Mercurial if it died before closing
its end of the pipe, whereas it will now cause Mercurial to exit.

diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
--- a/mercurial/dispatch.py
+++ b/mercurial/dispatch.py
@@ -147,7 +147,7 @@
 
     ui = req.ui
     try:
-        for name in 'SIGBREAK', 'SIGHUP', 'SIGTERM':
+        for name in 'SIGBREAK', 'SIGHUP', 'SIGTERM', 'SIGPIPE':
             num = getattr(signal, name, None)
             if num:
                 signal.signal(num, catchterm)