diff -r f41a99c45956 -r 41448fc51510 mercurial/sparse.py
--- a/mercurial/sparse.py	Thu Jul 06 12:14:12 2017 -0700
+++ b/mercurial/sparse.py	Thu Jul 06 12:06:37 2017 -0700
@@ -12,6 +12,11 @@
     error,
 )
 
+# Whether sparse features are enabled. This variable is intended to be
+# temporary to facilitate porting sparse to core. It should eventually be
+# a per-repo option, possibly a repo requirement.
+enabled = False
+
 def parseconfig(ui, raw):
     """Parse sparse config file content.