Fix edit of default layout

Closes tpope#425.

Author: tpope

autoload/rails.vim

@@ -2950,15 +2950,15 @@ function! s:viewEdit(cmd, ...) abort
   endif
 endfunction
 
-function! s:layoutEdit(cmd,...)
+function! s:layoutEdit(cmd,...) abort
   if a:0
     return s:viewEdit(a:cmd,"layouts/".a:1)
   endif
   let file = s:findlayout('')
   if file ==# ""
     let file = "app/views/layouts/application.html.erb"
   endif
-  return s:edit(a:cmd,s:sub(file,'^/',''))
+  return s:edit(a:cmd, file)
 endfunction
 
 function! s:stylesheetEdit(cmd,...)