--- a/mercurial/scmutil.py	Fri Jun 30 03:42:28 2017 +0200
+++ b/mercurial/scmutil.py	Fri Jun 30 03:42:29 2017 +0200
@@ -983,7 +983,7 @@
     """
     # experimental config: format.generaldelta
     return (ui.configbool('format', 'generaldelta')
-            or ui.configbool('format', 'usegeneraldelta', True))
+            or ui.configbool('format', 'usegeneraldelta'))
 
 def gddeltaconfig(ui):
     """helper function to know if incoming delta should be optimised