Fix route wrap

[wxiaoguang]

Because we introduced the new code:

• A few more improvements wxiaoguang/gitea#3

We must make sure every converted handler can return done=true correctly.

Otherwise, there will be duplicated calls to others again and again. Known problems caused by this bug:

• visit /api/swagger triggers panic
• many APIs return duplicated response

func wrapInternal(handlers []wrappedHandlerFunc) http.HandlerFunc {
	return func(resp http.ResponseWriter, req *http.Request) {
		var defers []func()
		defer func() {
			for i := len(defers) - 1; i >= 0; i-- {
				defers[i]()
			}
		}()
		for i := 0; i < len(handlers); i++ {
			handler := handlers[i]
			others := handlers[i+1:]
			done, deferrable := handler(resp, req, others...)
			if deferrable != nil {
				defers = append(defers, deferrable)
			}
			if done {
				return
			}
		}
	}
}