i.e. use --time-cond but suppress the header it generates with --header as described in the man page: "Remove an internal header by giving a replacement without content on the right side of the colon".
(For context, I'm also adding the If-None-Match header, so I do want the 304-means-keep-file behaviour that --time-cond provides, just with a different header.)
I expected the following
The generated If-Modified-Since header would be suppressed, like so:
GET /hello.txt HTTP/1.1