On the whole, the patch looks okay to me.  I think we should strive for correctness in the documentation where possible.

While keeping "True" would keep the forward implications correct and document the "preferred" value, there is often an implied assumption (which is sometimes stated) that the negation of the first term does not trigger or guarantee the behavior described in the second term.  It is that second implication that would be incorrect in some cases if "True" is kept (e.g. *check_circular* and *allow_nan*).

In cases where both "if True" and "if False" are explicitly stated, keeping "True" and "False" would mean not documenting certain cases.