public void cloneBugFilter() throws Exception {
add("file.txt", "content", "fixes NPE\nBug: abcd");
CommitCountFilter count = new CommitCountFilter();
BugFilter filter = new BugFilter();
RevFilter clone = filter.clone();
assertNotNull(clone);
assertNotSame(filter, clone);
new CommitFinder(testRepo).setFilter(
new AndCommitFilter(filter, clone, count)).find();