decimal behavior when casting floats in python 2.6 and 2.7

python26.log

tkaemming@reventon % python2.6                                                                                                                                ~
Python 2.6.6 (r266:84292, Jun 16 2011, 16:59:16) 
[GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decimal import Decimal
>>> Decimal(15.0/100.0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/decimal.py", line 649, in __new__
    "First convert the float to a string")
TypeError: Cannot convert float to Decimal.  First convert the float to a string

python27.log

tkaemming@reventon % python                                                                                                                                   ~
Python 2.7.1 (r271:86832, Jun 16 2011, 16:59:05) 
[GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decimal import Decimal
>>> Decimal(15.0/100.0)
Decimal('0.1499999999999999944488848768742172978818416595458984375')