partially revert e368a91

TTTLmabda does not seem to require exhaustive analysis for consistency reasons

Author: mtf90

algorithms/active/lambda/src/main/java/de/learnlib/algorithm/lambda/ttt/AbstractTTTLambda.java

@@ -70,7 +70,7 @@ public boolean refineHypothesis(DefaultQuery<I, D> counterexample) {
         witnesses.add(counterexample);
         boolean refined = false;
 
-        while (!witnesses.isEmpty()) {
+        while (MQUtil.isCounterexample(counterexample, getHypothesisModel())) {
             final DefaultQuery<I, D> witness = witnesses.getFirst();
 
             if (witness.getOutput() == null) {