It is possible to reproduce original bug without hacking the code object or bytecode:

>>> eval('lambda %s, *args, **kwargs: (lambda:args)' % (', '.join('a%d'%i for i in range(253)),))(*range(256))()
(253, 254, 255)
>>> eval('lambda %s, *args, **kwargs: (lambda:args)' % (', '.join('a%d'%i for i in range(254)),))(*range(256))()
(254, 255)
>>> eval('lambda %s, *args, **kwargs: (lambda:args)' % (', '.join('a%d'%i for i in range(255)),))(*range(256))()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1, in <lambda>
NameError: free variable 'args' referenced before assignment in enclosing scope

>>> eval('lambda %s, *args, **kwargs: (lambda:kwargs)' % (', '.join('a%d'%i for i in range(253)),))(*range(256))()
{}
>>> eval('lambda %s, *args, **kwargs: (lambda:kwargs)' % (', '.join('a%d'%i for i in range(254)),))(*range(256))()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1, in <lambda>
NameError: free variable 'kwargs' referenced before assignment in enclosing scope
>>> eval('lambda %s, *args, **kwargs: (lambda:kwargs)' % (', '.join('a%d'%i for i in range(255)),))(*range(256))()
0