[6.0] 2a0725c09 Incomplete condition

[Dridi Boukelmoune]

commit 2a0725c0930b09c120ef3912b7f96e41f162df0f
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Mon Mar 26 22:30:04 2018 +0200

    Incomplete condition

diff --git a/bin/varnishtest/vtc.c b/bin/varnishtest/vtc.c
index 62c83af14..8d7f76438 100644
--- a/bin/varnishtest/vtc.c
+++ b/bin/varnishtest/vtc.c
@@ -915,7 +915,7 @@ exec_file(const char *fn, const char *script, const char *tmpdir,
 		VSB_putc(vsb, '/');
 		VSB_bcat(vsb, fn, p - fn);
 	}
-	if (VSB_len == 0)
+	if (VSB_len(vsb) == 0)
 		VSB_putc(vsb, '/');
 	AZ(VSB_finish(vsb));
 	macro_def(vltop, NULL, "testdir", "%s", VSB_data(vsb));