How to respond with "410 Gone" for specific URLs

For SEO reasons I want to return "410 Gone" for some specific URLs which I will match using path_beg or path_sub.

I've tried the following:

frontend foo
    mode http
    bind :80

    # 1) this works but I cannot use 410
    http-request deny deny_status 408 if { path_sub bar }

    # 2) this doesn't work at all no matter the code
    http-response set-status 408 if { path_sub test }

I cannot use 410 in the first directive with http-request because https://cbonte.github.io/haproxy-dconv/1.8/configuration.html#errorfile:

<code> is the HTTP status code. Currently, HAProxy is capable of generating codes 200, 400, 403, 405, 408, 425, 429, 500, 502, 503, and 504.

The second directive with the http-response doesn't have any effect.

How can I return a 410?