diff -r d19804c16710 -r 4531a967e7f1 mercurial/vfs.py
--- a/mercurial/vfs.py	Fri Jun 30 03:45:59 2017 +0200
+++ b/mercurial/vfs.py	Fri Jun 30 03:46:00 2017 +0200
@@ -550,7 +550,7 @@
         # Windows defaults to a limit of 512 open files. A buffer of 128
         # should give us enough headway.
         maxqueue = ui.configint('worker', 'backgroundclosemaxqueue')
-        threadcount = ui.configint('worker', 'backgroundclosethreadcount', 4)
+        threadcount = ui.configint('worker', 'backgroundclosethreadcount')
 
         ui.debug('starting %d threads for background file closing\n' %
                  threadcount)