bug#33141: 27.0.50; TRAMP simplified syntax doesn't work

[Dima Kogan]

Hi.

Currently the simplified TRAMP syntax doesn't work. I'm at a recent
(2018/9/8) build: e4896856172

I do this:

1. emacs -Q
2. (require 'tramp)
3. (tramp-change-syntax 'simplified)
4. I try to open a file with the simplified syntax
   - C-x C-f
   - /localhost:

I see this:

tramp-file-name-handler: Wrong type argument: stringp, ""

Thanks