diff --git a/mercurial/context.py b/mercurial/context.py
--- a/mercurial/context.py
+++ b/mercurial/context.py
@@ -9,14 +9,7 @@ from node import nullid, nullrev, short,
 from i18n import _
 import ancestor, bdiff, error, util, os, errno
 
-class propertycache(object):
-    def __init__(self, func):
-        self.func = func
-        self.name = func.__name__
-    def __get__(self, obj, type=None):
-        result = self.func(obj)
-        setattr(obj, self.name, result)
-        return result
+propertycache = util.propertycache
 
 class changectx(object):
     """A changecontext object makes access to data related to a particular
diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -137,6 +137,15 @@ def cachefunc(func):
 
     return f
 
+class propertycache(object):
+    def __init__(self, func):
+        self.func = func
+        self.name = func.__name__
+    def __get__(self, obj, type=None):
+        result = self.func(obj)
+        setattr(obj, self.name, result)
+        return result
+
 def pipefilter(s, cmd):
     '''filter string S through command CMD, returning its output'''
     (pin, pout) = popen2(cmd, 'b')