delete kept folder, see IDEA-CR-4598 - preserve extra kept files

platform/testFramework/src/com/intellij/testFramework/LightPlatformTestCase.java

@@ -736,11 +736,11 @@ public abstract class LightPlatformTestCase extends UsefulTestCase implements Da
 
       ProjectManagerEx.getInstanceEx().closeAndDispose(ourProject);
 
-      // project may be disposed but folder is still there
+      // project may be disposed but empty folder may still be there
       if (ourPathToKeep != null) {
         File parent = new File(ourPathToKeep).getParentFile();
         if (parent.getName().startsWith(UsefulTestCase.TEMP_DIR_MARKER)) {
-          FileUtil.delete(parent);
+          parent.delete(); // delete only empty folders
         }
       }