reduce() anomaly?

[Stephen C. Waterbury]

This seems like it ought to work, according to the
description of reduce(), but it doesn't.  Is this
a bug, or am I missing something?

Python 2.3.2 (#1, Oct 20 2003, 01:04:35)
[GCC 3.2.2 20030222 (Red Hat Linux 3.2.2-5)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
 >>> d1 = {'a':1}
 >>> d2 = {'b':2}
 >>> d3 = {'c':3}
 >>> l = [d1, d2, d3]
 >>> d4 = reduce(lambda x, y: x.update(y), l)
Traceback (most recent call last):
   File "<stdin>", line 1, in ?
   File "<stdin>", line 1, in <lambda>
AttributeError: 'NoneType' object has no attribute 'update'
 >>> d4 = reduce(lambda x, y: x.update(y), l, {})
Traceback (most recent call last):
   File "<stdin>", line 1, in ?
   File "<stdin>", line 1, in <lambda>
AttributeError: 'NoneType' object has no attribute 'update'

- Steve.