Why are True and 1 equivalent as dictionary keys?

Question

I got a quite strange bug in my code... at some point I have to convert values to unicode strings, with the exception of some special values (None, True, False) that need special treatment.

The code looks something like this:

conversions = {
    None: 'null',
    True: 'true',
    False: 'false',
}

def translate(val):
    return conversions.get(val, unicode(val))

But when the value 1 is passed in, I got back u'true' while I was expecting u'1'. So I opened a console and played a little bit:

Python 2.7.5 (default, May 15 2013, 22:43:36) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> d = {True: 'yeah', False: 'boooh'}

>>> d[1]
'yeah'
>>> d[0]
'boooh'

>>> 1 in d
True
>>> 0 in d
True

>>> True is 1
False

So, it turns out that 0 and 1 behave the same way as True and False. Why? it is confusing and leads to strange bugs like this...