[Bug]: python trivial inferencing code fails when dealing with unpacking+generators

[hjtran]

What happened?

The following unit test (you can drop it into trivial_inference_test.py) fails

 def testNestedUnpack(self):
    def nest_in_list(x, y):
      return [(x, y) for _ in range(1)]
    self.assertReturnType(
        typehints.List[typehints.Tuple[str, int]],
        lambda x: nest_in_list(*x), [typehints.Tuple[str, int]])

Expected :List[Tuple[<class 'str'>, <class 'int'>]]
Actual   :List[Tuple[<class 'type'>, <class 'type'>]]

This can cause issues with certain callables. For example:
#33014

Issue Priority

Priority: 2 (default / most bugs should be filed as P2)

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