TEST: Add a test that is cmdsn is too low the target just ignores the pdu

test-tool/iscsi-test-cu.h

@@ -50,6 +50,7 @@ void test_inquiry_supported_vpd(void);
 void test_inquiry_mandatory_vpd_sbc(void);
 
 void test_iscsi_cmdsn_toohigh(void);
+void test_iscsi_cmdsn_toolow(void);
 
 void test_mandatory_sbc(void);