move the http_gzip_support check to the right place

Ref: #2610

Thank you to @fgsch for spotting

Apologies to everyone for my insufficient understanding of the agreement
about which fixes we push during the soak in period after release.

bin/varnishd/cache/cache_fetch.c

@@ -521,11 +521,6 @@ vbf_figure_out_vfp(struct busyobj *bo)
 	 *
 	 */
 
-	if (! cache_param->http_gzip_support) {
-		bo->do_gzip = bo->do_gunzip = 0;
-		return (0);
-	}
-
 	if (http_GetStatus(bo->beresp) == 206) {
 		if (bo->do_esi) {
 			VSLb(bo->vsl, SLT_VCL_Error,
@@ -536,6 +531,11 @@ vbf_figure_out_vfp(struct busyobj *bo)
 		return (0);
 	}
 
+	if (! cache_param->http_gzip_support) {
+		bo->do_gzip = bo->do_gunzip = 0;
+		return (0);
+	}
+
 	/* No body -> done */
 	if (bo->htc->body_status == BS_NONE ||
 	    bo->htc->content_length == 0) {