Fix setting the host header

src/vmod_zipflow.c

@@ -822,6 +822,7 @@ zfr_include(struct req *preq, struct zipflow_request *zfr)
 	struct vmod_priv *task_priv;
 	struct vrt_ctx ctx[1];
 	enum req_fsm_nxt s;
+	const char *h;
 
 	CHECK_OBJ_NOTNULL(preq, REQ_MAGIC);
 	CHECK_OBJ_NOTNULL(preq->top, REQTOP_MAGIC);
@@ -862,7 +863,8 @@ zfr_include(struct req *preq, struct zipflow_request *zfr)
 	http_SetH(req->http, HTTP_HDR_URL, zfr->uri);
 	if (zfr->host != NULL && *zfr->host != '\0')  {
 		http_Unset(req->http, H_Host);
-		http_SetHeader(req->http, zfr->host);
+		h = WS_Printf(req->ws, "Host: %s", zfr->host);
+		http_SetHeader(req->http, h);
 	}
 
 	http_ForceField(req->http, HTTP_HDR_METHOD, "GET");