Cannot execute failed tests

[dfiloni]

Hi,
I used umap2kitty to record a session (with -f flag) and then I tried to execute again failed tests (with -r flag) however umap2fuzz crashes with the following error:

Exception: Got error from RPC server when called "start" error: {u'message': u'exception in call "start({})" -> Specified test range exceeds the maximum mutation count', u'code': -32603}

The same issue is the one described in #25 (same trace).

To avoid this error as "fast workaround", I changed the RangesList class set_last function in kitty/fuzzers/test_list.py file as follows, then the tests re-execution worked fine.

    def set_last(self, last):
        last_list = self._lists[-1]
        if last > last_list._start and last_list.open_ended():
            last_list.set_last(last)