Calling http.FileServer in an http.HandlerFunc

so I've had some trouble with this lately... Here is my code:

https://gist.github.com/anonymous/af1e6d922ce22597099521a4b2cfa16f

My problem: I'm trying to serve up some HTML files from a folder: ./docs/html. My folder structure:

.
├── docs
│   └── html
│       ├── index.html
│       └── rest.html
└── main.go

You'll notice in the gist I am calling the ServeHTTP method on the http.HandlerFunc ServeDocs, which is then going through a router (mux.Router). The problem I'm having is for some reason the only file being served up at localhost:8080/ is index.html, and when I navigate to localhost:8080/rest.html I get a 404.

The really odd part is that when I remove all the router code and do something like the following:

fs := http.FileServer(http.Dir("./docs/html"))
http.Handle("/", fs)

log.Println("Listening...")
http.ListenAndServe(":3000", nil)

Everything works as it should. Anybody know what's going on? I've spent hours trying to figure this out and I've finally given up.

It works if you use mux.Router's Path method

> r.Methods(route.Method).Name(route.Name).Handler(handler)
> r.Path(route.Pattern)

instead of mux.Route's Path method (strikethrough'd below)

> r.Methods(route.Method)<s>.Path(route.Pattern)</s>.Name(route.Name).Handler(handler)

I am not much familiar with gorilla/mux so couldn't find exact reason behind this.