mercurial/configitems.py

--- a/mercurial/configitems.py	Mon Nov 20 10:27:41 2017 -0800
+++ b/mercurial/configitems.py	Sun Dec 17 11:26:25 2017 -0800
@@ -1253,6 +1253,9 @@
 coreconfigitem('worker', 'backgroundclosethreadcount',
     default=4,
 )
+coreconfigitem('worker', 'enabled',
+    default=True,
+)
 coreconfigitem('worker', 'numcpus',
     default=None,
 )