This is some very old patch series, initially aimed at speeding up Gears of Wars online connection, but it wasn't clear if it was actually necessary.
We now confirmed that it is also required for Gears 5 online mode, and without it, connection fails with an error message. I updated the last change to specifically handle TLS rehandshake vs empty input, to avoid breaking some tests. I think having empty input when renegotiating is a valid scenario, although I'm not sure how to write tests for that (it will require some server-side part to request a re-handshake to the client).
In any case, this has nothing to do with client certificate as the returned ERROR_WINHTTP_CLIENT_AUTH_CERT_NEEDED error in the code seems to suggest.
-- v2: secur32: Perform TLS re-handshake after SEC_I_RENEGOTIATE was returned. winhttp: Handle SEC_I_RENEGOTIATE after DecryptMessage. winhttp: Introduce new netconn_negotiate helper. winhttp: Move connect end checks out of the loop.