'MySQL does not support defaults on text or blob columns.'

def _alter_set_defaults(self, field, name, params, sqls):

    type = params['type']
    is_geom = (True in [(type.find(t) > (-1)) for t in self.geom_types])
    is_text = (True in [(type.find(t) > (-1)) for t in self.text_types])
    if ((not is_geom) and (not is_text)):
        super(DatabaseOperations, self)._alter_set_defaults(field, name, params, sqls)
