current blobcode with varnish 5.0 supports init'ing from transient blob - mark TODO

we would need to complicate testing specifically, so just mark this as
a TODO for now

src/tests/md5.vtc

@@ -345,6 +345,10 @@ varnish v1 -vcl {
 		new k1 = blobcode.blob(HEX, "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b");
 		new rfc2202t1 = blobdigest.hmac(MD5, k1.get());
 
+		# ONLY for >= 5.0 - TODO: separate test?
+		# new rfc2202t1b = blobdigest.hmac(MD5,
+		#   blobcode.decode(encoded="0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b"));
+
 		new k2 = blobcode.blob(IDENTITY, "Jefe");
 		new rfc2202t2 = blobdigest.hmac(MD5, k2.get());