[web2py] Internationalization of invalidators' error_message

[dlin]

I don't understand why not the invalidators' error_message only use
English.
eg.
class IS_NOT_EMPTY(Validator):
    def __init__(self, error_message='enter a value',
empty_regex=None):

why not

class IS_NOT_EMPTY(Validator):
    def __init__(self, error_message=T('enter a value'),
empty_regex=None):

I don't want to assign every IS_NOT_EMPTY's error_message.