Bool tag doesn't accept all defined variants

[anonymous]

One of the examples listed at  http://yaml.org/type/bool.html will fail:

>>> yaml.load('!!bool y')
Traceback (most recent call last):
 ...
KeyError: u'y'

[xi]

The type description at  http://yaml.org/type/bool.html is obsolete. Having 'y' as a boolean value is really a bad idea since it is often used in other contexts (for instance, as a coordinate). Syck does not support it, neither will PyYAML.