Serving "/" from FileServer using embedded Filesystem results in HTTP 404

[mtrense]

Version
v0.0.0-20191006184023-c8e73f4f4df2

Describe the bug
Following https://github.com/kataras/iris/wiki/File-server and #1283, when serving from an embedded Filesystem like

app.HandleDir("/", "./web/build", iris.DirOptions{
	Asset:      static.Asset,
	AssetInfo:  static.AssetInfo,
	AssetNames: static.AssetNames,
	Gzip: false,
})

with a file ./web/build/index.html present, requesting http://localhost:8080/ results in a HTTP 404.

To Reproduce
Steps to reproduce the behavior:

1. Bundle an index.html using go-bindata
2. Add route with HandleDir as described above
3. Request http://localhost:8080/

Expected behavior
Content of index.html should be returned

Screenshots
n/a

Desktop (please complete the following information):
n/a

Additional context
While debugging I found that the Handler returned from FileServer in

iris/core/router/fs.go

Line 341 in c8e73f4

f, err := fs.Open(name)

already returns with http.StatusNotFound when name is /. This works when using the filesystem, but not for the embedded filesystem. Line 355, where the special handling for the root-URL should happen is thus never reached.