-----BEGIN EC PRIVATE KEY-----
MHcCAQEEIDID8g9mX4QhBstI0asSOwAbetxN13PaA5YoVLsQgp8SoAoGCCqGSM49
AwEHoUQDQgAEQDCysAPobKehaA/R5mKepHOnr7y/nXifgsDXkYK9qEj6SM0cZ2oR
f3pQlwPrd+3i4DB9RSu1Ok8cAkACpJfu+g==
-----END EC PRIVATE KEY-----

This key is generated using

$ openssl ecparam -genkey -name prime256v1 -noout -out private_key.pem

and isn't used anywhere. so, it's safe to have this checked into version control.
It is generated to avoid internal functions, for e.g. `generate_client_secret`,
of python-social-auth from failing because of a private key missing.