replace 'cond and one or tother' idiom with 'one if cond or tother'

[daira]

In Python 2.5, the nearest equivalent to C's cond ? one : tother was the idiom cond and one or tother. In Python 2.6, a more precise equivalent is one if cond else tother.

The former is error-prone: it evaluates to tother when one is falsy, which is the wrong thing. Since we now depend on Python 2.6, we can always use the latter.

("t'other" is Northern English dialect for "the other", if you were wondering about that.)