Changed exception log message in whoosh backend to use __class__.__name__ instead of just __name__ (closes django-haystack#641)

Author: jtratner

haystack/backends/whoosh_backend.py

@@ -186,7 +186,7 @@ def update(self, index, iterable, commit=True):
                 # We'll log the object identifier but won't include the actual object
                 # to avoid the possibility of that generating encoding errors while
                 # processing the log message:
-                self.log.error(u"%s while preparing object for update" % e.__name__, exc_info=True, extra={
+                self.log.error(u"%s while preparing object for update" % e.__class__.__name__, exc_info=True, extra={
                     "data": {
                         "index": index,
                         "object": get_identifier(obj)