Works fine on a 32-bit Linux build (64-bit machine, though):

>>> import sys
>>> sys.maxsize
2147483647
>>> a = {}
>>> for k in range(1000000): a['a' * k] = k
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
MemoryError
>>> del a
>>> a = {}
>>> for k in range(1000000): a[k] = k
... 
>>> 


Note that Linux says the process eats 4GB RAM.