Correct the test of a big number (2 ^ 31) (#26491)
Summary:
2 ^ 31 is 29, which is not a big number. Corrected to 2 ** 31.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26491
Differential Revision: D17494296
fbshipit-source-id: 83d320e8fb6d1b7df41e4474933a98107c8e4129
