using anyauth isn't unconditionally an extra roundtrip

.IP "--anyauth"

(HTTP) Tells curl to figure out authentication method by itself, and use the

most secure one the remote site claims it supports. This is done by first

doing a request and checking the response-headers, thus inducing an extra

network round-trip. This is used instead of setting a specific authentication

method, which you can do with \fI--basic\fP, \fI--digest\fP, \fI--ntlm\fP, and

\fI--negotiate\fP.

doing a request and checking the response-headers, thus possibly inducing an

extra network round-trip. This is used instead of setting a specific

authentication method, which you can do with \fI--basic\fP, \fI--digest\fP,

\fI--ntlm\fP, and \fI--negotiate\fP.

Note that using --anyauth is not recommended if you do uploads from stdin,

since it may require data to be sent twice and then the client must be able to

(Added in 7.17.1)

.IP "--proxy-anyauth"

Tells curl to pick a suitable authentication method when communicating with

the given proxy. This will cause an extra request/response round-trip. (Added

the given proxy. This might cause an extra request/response round-trip. (Added

in 7.13.2)

If this option is used twice, the second will again disable the proxy use-any