mercurial/configitems.py

--- a/mercurial/configitems.py	Tue Oct 10 17:50:27 2017 +0200
+++ b/mercurial/configitems.py	Sat Oct 14 17:05:41 2017 +0200
@@ -417,6 +417,9 @@
 coreconfigitem('experimental', 'sparse-read.density-threshold',
     default=0.25,
 )
+coreconfigitem('experimental', 'sparse-read.min-block-size',
+    default='256K',
+)
 coreconfigitem('experimental', 'treemanifest',
     default=False,
 )