DynamicBanScore String() Deadlock

[lochjin]

// String returns the ban score as a human-readable string.
func (s *DynamicBanScore) String() string {
	s.mtx.Lock()
	r := fmt.Sprintf("persistent %v + transient %v at %v = %v as of now",
		s.persistent, s.transient, s.lastUnix, s.Int())
	s.mtx.Unlock()
	return r
}

// Int returns the current ban score, the sum of the persistent and decaying
// scores.
//
// This function is safe for concurrent access.
func (s *DynamicBanScore) Int() uint32 {
	s.mtx.Lock()
	r := s.int(time.Now())
	s.mtx.Unlock()
	return r
}

s.Int() will cause deadlock。So I fixed it #1509

[jakesylvestre]

Fixed in #1509