Use hmac.compare_digest for value comparison (#346)
Use hmac.compare_digest for value comparison (#346)

* Use hmac.compare_digest for value comparison

`hmac.compare_digest` is available in both Python 2/3
and provides time constant comparison of ascii and binary
values. It is safe for cryptographic use to prevent timing
attacks.
python-social-auth/social-core,python-social-auth/social-core