Index: /trunk/test/unit/org/openstreetmap/josm/testutils/JOSMTestRules.java
===================================================================
--- /trunk/test/unit/org/openstreetmap/josm/testutils/JOSMTestRules.java	(revision 18550)
+++ /trunk/test/unit/org/openstreetmap/josm/testutils/JOSMTestRules.java	(revision 18551)
@@ -27,4 +27,5 @@
 import java.util.logging.Level;
 
+import mockit.internal.state.SavePoint;
 import org.awaitility.Awaitility;
 import org.junit.jupiter.api.extension.AfterAllCallback;
@@ -729,4 +730,6 @@
         @Override
         public void evaluate() throws Throwable {
+            // Needed since JMockit doesn't clean up JUnit4 vintage tests. We really shouldn't have to touch JMockit internal classes. :(
+            SavePoint savePoint = new SavePoint();
             before();
             try {
@@ -735,4 +738,5 @@
                 if (!junit5) {
                     after();
+                    savePoint.rollback();
                 }
             }