fix test case

Author: wadoon

key.core.testgen/src/test/java/de/uka/ilkd/key/testcase/smt/ce/TestCE.java

@@ -139,7 +139,7 @@ public void testMiddle() throws Exception {
             TryCloseMacro close = new TryCloseMacro();
             close.applyTo(env.getUi(), proof, proof.openEnabledGoals(), null, null);
             // should not be provable
-            assertFalse(!proof.openGoals().isEmpty());
+            assertFalse(proof.openGoals().isEmpty());
             // there should be a counterexample for each goal...
             for (Goal g : proof.openGoals()) {
                 SemanticsBlastingMacro sb = new SemanticsBlastingMacro();