copy the include path, it is owned by the caller

The src argument of vped_include() is owned by the caller
vdp_pesi_bytes(), so we need to make a copy on the subrequest's
workspace.

This is not an issue with varnish-cache ESI because the include is
not handed over to a different thread.

src/vdp_pesi.c

@@ -339,7 +339,7 @@ vped_include(struct req *preq, const char *src, const char *host,
 	HTTP_Setup(req->http, req->ws, req->vsl, SLT_ReqMethod);
 	HTTP_Dup(req->http, preq->http0);
 
-	http_SetH(req->http, HTTP_HDR_URL, src);
+	http_SetH(req->http, HTTP_HDR_URL, WS_Copy(req->ws, src, -1));
 	if (host != NULL && *host != '\0')  {
 		http_Unset(req->http, H_Host);
 		http_SetHeader(req->http, host);