Can't load Rails project when open Vim with a directory

[ThanhKhoaIT]

My context: (use NERDTree plugin)
Step 1. Goto project folder (Ex: cd ~/project/demo-app)
Step 2. Open vim with vim . (filetype=nerdtree) "." is a directory

I can't use the command (:Vmodel, :Vcontroller, etc...)

PS. I checked the rails loaded status with the command :echo rails#app() => the output is {}.
But I workaround with the command line is vim in Step 2, to open Vim without a file/directory.

Can we add support for this case?
Change to autocmd FileType netrw,nerdtree in https://github.com/tpope/vim-rails/blob/master/plugin/rails.vim#L106