Message3241

The root of the problem is that PyString defines an __int__ method. 
__int__ is being used by the string formatter to convert any object to a 
number.

__int__ is really equivalent to CPython's tp_as_number nb_int. The 
tp_as_number interface in CPython is only defined for actual number 
types (float/long etc), not string.

__int__ really *is* what the string formatter should be calling (to get 
an integer from strictly numeric types) but the fact that PyString 
provides it means we get a conversion instead of an error here

CPython converts strings to ints (int('foo')) in a more explicit way; it 
first looks for the tp_as_number interface, and if that's not supported, 
explicitly checks for strings