From: Paul Molodowitch <pm@stanfordalumni.org>

bookmarks: fixes invalidaterepo check if repo._bookmarks is a property

also provides hglib.is_descriptor, which might be useful for other things

diff -r 4d75e31662d4 tortoisehg/util/hglib.py
--- a/tortoisehg/util/hglib.py	Thu Dec 24 12:53:17 2009 -0600
+++ b/tortoisehg/util/hglib.py	Thu Dec 24 12:27:59 2009 -0800
@@ -9,6 +9,7 @@
 import sys
 import shlex
 import time
+import inspect
 
 from mercurial import ui, util, extensions, match, bundlerepo, url
 from mercurial import dispatch, encoding, templatefilters, filemerge
@@ -147,8 +148,7 @@
     # from 1.4 to 1.5...
     for cachedAttr in ('_bookmarks', '_bookmarkcurrent'):
         # Check if it's a property or normal value...
-        classAttr = getattr(repo.__class__, cachedAttr, None)
-        if hasattr(classAttr, '__get__'):
+        if is_descriptor(repo, cachedAttr):
             # The very act of calling hasattr would
             # re-cache the property, so just assume it's
             # already cached, and catch the error if it wasn't.
@@ -381,3 +381,18 @@
         return False
     
     return rev == parents[0].node()
+
+def is_descriptor(obj, attr):
+    """
+    Returns True if obj.attr is a descriptor - ie, accessing
+    the attribute will actually invoke the '__get__' method of
+    some object.
+
+    Returns False if obj.attr exists, but is not a descriptor,
+    and None if obj.attr was not found at all.
+    """
+    for cls in inspect.getmro(obj.__class__):
+        if attr in cls.__dict__:
+            return hasattr(cls.__dict__[attr], '__get__')
+    return None
+