[Checkins] SVN: BTrees/branches/pure_python/ Preserve 'reason' semantics.

[Tres Seaver]

Log message for revision 128261:
  Preserve 'reason' semantics.

Changed:
  _U  BTrees/branches/pure_python/
  U   BTrees/branches/pure_python/BTrees/Interfaces.py

-=-
Modified: BTrees/branches/pure_python/BTrees/Interfaces.py
===================================================================
--- BTrees/branches/pure_python/BTrees/Interfaces.py	2012-11-12 20:31:03 UTC (rev 128260)
+++ BTrees/branches/pure_python/BTrees/Interfaces.py	2012-11-12 20:31:04 UTC (rev 128261)
@@ -511,7 +511,9 @@
     from ZODB.POSException import BTreesConflictError
 except ImportError:
     class BTreesConflictError(ValueError):
-        pass
+        @property
+        def reason(self):
+            return self.args[-1]
 
 ###############################################################
 # IMPORTANT NOTE