Message5712

This seems like a really bizarre edge case, perhaps not worth supporting.  
I'd argue it is a bug that CPython lets you do this with dict(), as it's not supported for ordinary Python functions.

>>> def f(**y): print y
... 
>>> f(x=3,y=7)
{'y': 7, 'x': 3}
>>> f(**{1: 3, 2: 7})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() keywords must be strings
>>> dict(**{1: 3, 2: 7})
{1: 3, 2: 7}