    @Test(expected = SignatureException.class)
    public void badSig() throws Exception {

        byte[] fakePatch = new byte[1024];
        Arrays.fill(fakePatch, (byte) 0x42);
        paths.put("/2.jar.bpatch", fakePatch);
        UFXProtocol.SignedUpdates.Builder builder = makeWrongIndex();
        builder.setSignatures(0, "bzzzz");
        paths.put("/index", builder.build().toByteArray());
        updater = new TestUpdater(indexURL, "UnitTest", dir, null);
        updater.call();
    }