configitems: register the 'format.usegeneraldelta' config

mercurial/configitems.py

@@ -128,6 +128,9 b" coreconfigitem('format', 'obsstore-versi"
 coreconfigitem('format', 'usefncache',
     default=True,
 )
+coreconfigitem('format', 'usegeneraldelta',
+    default=True,
+)
 coreconfigitem('hostsecurity', 'ciphers',
     default=None,
 )

mercurial/scmutil.py

@@ -983,7 +983,7 b' def gdinitconfig(ui):'
     """
     # 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