patch 7.4.2154
Problem:    Test_communicate() fails sometimes.
Solution:   Add it to the flaky tests.
diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index d7c0516..8f0c0c3 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -131,7 +131,7 @@
 endif
 
 " Names of flaky tests.
-let s:flaky = ['Test_reltime()', 'Test_nb_basic()']
+let s:flaky = ['Test_reltime()', 'Test_nb_basic()', 'Test_communicate()']
 
 " Locate Test_ functions and execute them.
 set nomore