The error is shown with infof rather than failf so that the user will
see the extended error message information only in verbose mode, and
will still see the standard CURLE_AUTH_ERROR message. For example:
---
* schannel: InitializeSecurityContext failed: SEC_E_QOP_NOT_SUPPORTED
(0x8009030A) - The per-message Quality of Protection is not supported by
the security package
* multi_done
* Connection #1 to host 127.0.0.1 left intact
curl: (94) An authentication function returned an error
---
Ref: https://github.com/curl/curl/issues/6302
Closes https://github.com/curl/curl/pull/6315
c54565915f