I got a crash with Python 2.5.2 :

Python 2.5.2 (r252:60911, Feb 21 2008, 13:11:45) [MSC v.1310 32 bit
(Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import decimal
>>> decimal.Decimal( 0 ).sqrt()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "f:\Python25\lib\decimal.py", line 2330, in sqrt
    return ans._fix(context)
  File "f:\Python25\lib\decimal.py", line 1461, in _fix
    Etiny = context.Etiny()
AttributeError: 'NoneType' object has no attribute 'Etiny'

I'll fix this.

Fixed in r61892 (2.6) and r61893 (2.5).  Thanks for the report!

This bug exposes a flaw in the decimal testsuite:  the thousands of 
testcases in Lib/test/decimaltestdata are only ever run with an explicitly 
given context.  Would it be worth having an option to run (almost all) 
these tests with an implicit context as well, or even to
do this by default in addition to the explicit context testing?

It'd be nice to have it, but actually I'm not sure that this is doable
without some heavy editing of decimal's test framework.

Thanks!