Infinite recursion when opening file via "/ssh:host|sudo:host:"

[iskur]

Describe
Upon opening a file with tramp's ad-hoc multihop feature, emacs enters an infinite recursion.

Steps and Expected
I started emacs with emacs -Q and evaluated the following code:

(require 'package)
(let* ((no-ssl (and (memq system-type '(windows-nt ms-dos))
                    (not (gnutls-available-p))))
       (proto (if no-ssl "http" "https")))
  (when no-ssl
    (warn "\
Your version of Emacs does not support SSL connections,
which is unsafe because it allows man-in-the-middle attacks.
There are two things you can do about this warning:
1. Install an Emacs version that does support SSL and be safe.
2. Remove this warning from your init file so you won't see it again."))
  ;; Comment/uncomment these two lines to enable/disable MELPA and MELPA Stable as desired
  (add-to-list 'package-archives (cons "melpa" (concat proto "://melpa.org/packages/")) t)
  ;;(add-to-list 'package-archives (cons "melpa-stable" (concat proto "://stable.melpa.org/packages/")) t)
  (when (< emacs-major-version 24)
    ;; For important compatibility libraries like cl-lib
    (add-to-list 'package-archives (cons "gnu" (concat proto "://elpa.gnu.org/packages/")))))
(package-initialize)
(package-install 'doom-modeline)
(require 'doom-modeline)
(doom-modeline-mode 1)
(find-file "/ssh:cubox|sudo:cubox:/root/.zshrc")

I expect the file to be opened.

Environment:

• ArchLinux
• GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.12, cairo version 1.17.3)
• doom-modeline 20191027.1850

Additional context
Traceback from enabling toggle-debug-on-quit and hitting C-g:

Debugger entered--Lisp error: (quit "nil")
  signal(quit ("nil"))
  tramp-signal-hook-function(quit nil)
  get-buffer-create(" *temp*-665421")
  #f(compiled-function (name) "Create and return a buffer with a name based on NAME.\nChoose the buffer's name using `generate-new-buffer-name'." #<bytecode 0x1fdea9f7f729>)(" *temp*")
  apply(#f(compiled-function (name) "Create and return a buffer with a name based on NAME.\nChoose the buffer's name using `generate-new-buffer-name'." #<bytecode 0x1fdea9f7f729>) " *temp*")
  generate-new-buffer(" *temp*")
  format-spec("ssh:cubox|" ((104 . "cubox") (117 . #("root" 0 4 (tramp-default t)))))
  tramp-dissect-file-name(#("/ssh:cubox|sudo:root@cubox:/root/.bash_history" 16 20 (tramp-default t)))
  tramp-file-name-handler(expand-file-name #("/ssh:cubox|sudo:root@cubox:/root/.bash_history" 16 20 (tramp-default t)) nil)
  file-exists-p(#("/ssh:cubox|sudo:root@cubox:/root/.bash_history" 16 20 (tramp-default t)))
  doom-modeline-update-buffer-file-state-icon(" *temp*")
  apply(doom-modeline-update-buffer-file-state-icon " *temp*")
  generate-new-buffer(" *temp*")
...
  generate-new-buffer(" *temp*")
  format-spec("ssh:cubox|" ((104 . "cubox") (117 . #("root" 0 4 (tramp-default t)))))
  tramp-dissect-file-name(#("/ssh:cubox|sudo:root@cubox:/root/.bash_history" 16 20 (tramp-default t)))
  tramp-file-name-handler(expand-file-name #("/ssh:cubox|sudo:root@cubox:/root/.bash_history" 16 20 (tramp-default t)) nil)
  file-exists-p(#("/ssh:cubox|sudo:root@cubox:/root/.bash_history" 16 20 (tramp-default t)))
  doom-modeline-update-buffer-file-state-icon(" *temp*")
  apply(doom-modeline-update-buffer-file-state-icon " *temp*")
  generate-new-buffer(" *temp*")
  format-spec("ssh:cubox|" ((104 . "cubox") (117 . #("root" 0 4 (tramp-default t)))))
  tramp-dissect-file-name(#("/ssh:cubox|sudo:root@cubox:/root/.bash_history" 16 20 (tramp-default t)))
  tramp-file-name-handler(file-remote-p #("/ssh:cubox|sudo:root@cubox:/root/.bash_history" 16 20 (tramp-default t)) nil connected)
  file-remote-p(#("/ssh:cubox|sudo:root@cubox:/root/.bash_history" 16 20 (tramp-default t)) nil connected)
  tramp-sh-handle-verify-visited-file-modtime(#<buffer .bash_history>)
  apply(tramp-sh-handle-verify-visited-file-modtime #<buffer .bash_history>)
  tramp-sh-file-name-handler(verify-visited-file-modtime #<buffer .bash_history>)
  apply(tramp-sh-file-name-handler verify-visited-file-modtime #<buffer .bash_history>)
  tramp-file-name-handler(verify-visited-file-modtime #<buffer .bash_history>)
  verify-visited-file-modtime(#<buffer .bash_history>)
  find-file-noselect("/ssh:cubox|sudo:cubox:/root/.bash_history" nil nil nil)
  find-file("/ssh:cubox|sudo:cubox:/root/.bash_history")
  eval-buffer()  ; Reading at buffer position 1138
  funcall-interactively(eval-buffer)
  call-interactively(eval-buffer record nil)
  command-execute(eval-buffer record)
  execute-extended-command(nil "eval-buffer" "eval-bu")
  funcall-interactively(execute-extended-command nil "eval-buffer" "eval-bu")
  call-interactively(execute-extended-command nil nil)
  command-execute(execute-extended-command)

Edit: replaced the traceback with one from the minimal example and added `package-install 'doom-modeline) there.

[seagle0128]

Did you just try (find-file "/ssh:cubox|sudo:cubox:/root/.zshrc") in emacs -Q? I couldn't run it, either.

[iskur]

Yes, that works in emacs -Q without doom-modeline for me. You have to replace cubox with a hostname of a machine you have ssh-access to.

[seagle0128]

I can run (find-file "/ssh:cubox@cubox:/root/.zshrc"). Can you try it?

I cannot run it using sudo in emacs -Q.

Tramp: Opening connection for root@192.168.31.1 using sudo...failed

[iskur]

Using just a single hop in the form "/ssh:user@host:/somefile" works with doom-modeline (I checked it again). Only when doing a multihop like "/ssh:user@host|sudo:host:/somefile" the above infinite recursion occurs.

Multihop is really useful when doing sysadmin work. I can disable root-login at the server, but still edit there as root with emacs running locally.

Might it be the pipe character | that causes problems here?

[iskur]

I cannot run it using sudo in emacs -Q.

Tramp: Opening connection for root@192.168.31.1 using sudo...failed

It might be helpful to increase verbosity with (setq tramp-verbose 9) and take a look at the respective tramp buffer.
Or have you tried ssh-ing into 192.168.31.1 with a terminal?