bug#32363: 27.0.50; Sporadic file-notify test error on Cygwin

[Ken Brown <kbrown@cornell.edu>]

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file-notify-test04-autorevert fails sporadically on Cygwin, due to
timing issues.  The attached patch seems to fix it.  I've run it in a
loop of 100 trials several times, on two different computers, with no
failures.

Ken

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From 12eaf6fa377b7d19359a7af4ae486e2c4a61c965 Mon Sep 17 00:00:00 2001
From: Ken Brown <kbrown@cornell.edu>
Date: Fri, 3 Aug 2018 10:37:04 -0400
Subject: [PATCH] Fix a filenotify test failure on Cygwin

* test/lisp/filenotify-tests.el
(file-notify-test04-autorevert): Increase a sleep-for time
from 2 to 3 on Cygwin.  This avoids sporadic failures of the
test.  (Bug#99999)
---
 test/lisp/filenotify-tests.el | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/lisp/filenotify-tests.el b/test/lisp/filenotify-tests.el
index 56403f4309..612ea8cd7f 100644
--- a/test/lisp/filenotify-tests.el
+++ b/test/lisp/filenotify-tests.el
@@ -891,9 +891,9 @@ file-notify--test-with-events
 
 	    ;; Modify file.  We wait for two seconds, in order to
 	    ;; have another timestamp.  One second seems to be too
-            ;; short.
+            ;; short.  And Cygwin sporadically requires more than two.
             (ert-with-message-capture captured-messages
-              (sleep-for 2)
+              (sleep-for (if (eq system-type 'cygwin) 3 2))
               (write-region
                "foo bla" nil file-notify--test-tmpfile nil 'no-message)
 
-- 
2.17.0