Small fix in tsig_sign().

In old (pre-rrset-change) version, the TSIG error was set only in
case it was BADTIME. I'm not sure whether any other error can get
into this function, but it does not matter, it should behave in
the same way as before.

src/libknot/tsig-op.c

@@ -486,7 +486,10 @@ int knot_tsig_sign(uint8_t *msg, size_t *msg_len,
 	}
 
 	/* Create rdata for TSIG RR. */
-	tsig_create_rdata(tmp_tsig, key->algorithm, tsig_rcode);
+	tsig_create_rdata(tmp_tsig, key->algorithm, 
+	                  (tsig_rcode == KNOT_TSIG_RCODE_BADTIME) 
+	                    ? tsig_rcode
+	                    : 0);
 	tsig_rdata_set_alg(tmp_tsig, key->algorithm);
 
 	/* Distinguish BADTIME response. */