--- a/mercurial/demandimport.py	Mon Feb 10 00:43:54 2014 +0100
+++ b/mercurial/demandimport.py	Mon Feb 10 14:51:06 2014 -0800
@@ -162,6 +162,9 @@
     'mimetools',
     ]
 
+def isenabled():
+    return __builtin__.__import__ == _demandimport
+
 def enable():
     "enable global demand-loading of modules"
     __builtin__.__import__ = _demandimport