Tramp+bookmark crash when setting a different tramp-persistency-file-name file location

Question

I have set tramp-persistency-file-name to a custom location since I want all the files generated by emacs stored in a specific location.

(setq files-dir "~/src/emacs.d/vendor/files/")
(setq custom-file (concat files-dir "custom.el")
      tramp-persistency-file-name (concat files-dir "tramp")
      host-file (concat hosts-dir (replace-regexp-in-string "[^A-Za-z0-9_-]" "-" (downcase (car (split-string (system-name) "\\.")))) ".el")
      version-file (concat versions-dir (number-to-string emacs-major-version) ".el"))

I do have some bookmarks set to some remote locations, that are supposed to use tramp to reach some remote files.

So, the "first time" I use it, it works. I can reach my /scp:host:/path remote path and open some files.

Then, Tramp generates the history file in the right location I've set (~/src/emacs.d/vendor/files/tramp).

But the next time, I want to open such a location, it crashes and generates this backtrace:

Debugger entered--Lisp error: (invalid-function (["scp" nil "my-host" nil nil] ("locale" "LC_ALL=en_US.utf8") ("uname" "Linux 3.2.0-4-amd64") ("test" "test") ("remote-path" ("/bin" "/usr/bin" "/sbin" "/usr/sbin" "/usr/local/bin" "/usr/local/sbin")) ("remote-shell" "/bin/sh") ("stat" "\\stat") ("file-exists" "test -e") ("id" "/usr/bin/id") ("gid-string" "my-user") ("ls" "/bin/ls --color=never") ("ls-dired" t) ("gid-integer" 1016) ("perl-file-spec" t) ("perl-cwd-realpath" t) ("perl" "\\perl") ("readlink" "\\readlink")))
  ((["scp" nil "my-host" nil nil] ("locale" "LC_ALL=en_US.utf8") ("uname" "Linux 3.2.0-4-amd64") ("test" "test") ("remote-path" ("/bin" "/usr/bin" "/sbin" "/usr/sbin" "/usr/local/bin" "/usr/local/sbin")) ("remote-shell" "/bin/sh") ("stat" "\\stat") ("file-exists" "test -e") ("id" "/usr/bin/id") ("gid-string" "my-user") ("ls" "/bin/ls --color=never") ("ls-dired" t) ("gid-integer" 1016) ("perl-file-spec" t) ("perl-cwd-realpath" t) ("perl" "\\perl") ("readlink" "\\readlink")))
  eval-buffer(#<buffer  *load*> nil "/Users/my-user/src/emacs.d/vendor/files/tramp" nil t)  ; Reading at buffer position 702
  load-with-code-conversion("/Users/my-user/src/emacs.d/vendor/files/tramp" "/Users/my-user/src/emacs.d/vendor/files/tramp" nil t)
  load("tramp" nil t)
  (let ((default-directory (or (symbol-value (quote temporary-file-directory)) "/"))) (load "tramp" nil t))
  tramp-autoload-file-name-handler(expand-file-name "/scp:my-host:/home/my-user/my/path" nil)
  file-readable-p("/scp:my-host:/home/my-user/my/path")
  bookmark-default-handler(("MyBookmark" (filename . "/scp:my-host:/home/my-user/my/path")))
  byte-code("\301!\206�\302\303!!\207" [bookmark-name-or-record bookmark-get-handler bookmark-default-handler bookmark-get-bookmark] 3)
  bookmark-handle-bookmark("MyBookmark")
  bookmark--jump-via("MyBookmark" switch-to-buffer)
  bookmark-jump("MyBookmark")
  bookmark-bmenu-this-window()
  call-interactively(bookmark-bmenu-this-window nil nil)
  command-execute(bookmark-bmenu-this-window)

Note: if I comment the line setq tramp-persistency-file-name blabla, it solves the problem but the file is located in my emacs.d directory (which I do not want).

Do you have any idea what's going wrong ? Should I report a bug or am I the bug ?

EDIT: as requested here is the tramp file generated after the first use of the feature

;; -*- emacs-lisp -*- <15/12/23 10:35:22 ~/src/emacs.d/vendor/files/tramp>
;; Tramp connection history.  Don't change this file.
;; You can delete it, forcing Tramp to reapply the checks.

((["scp" nil "my-host" nil nil]
  ("locale" "LC_ALL=en_US.utf8")
  ("uname" "Linux 3.2.0-4-amd64")
  ("test" "test")
  ("remote-path"
   ("/bin" "/usr/bin" "/sbin" "/usr/sbin" "/usr/local/bin" "/usr/local/sbin"))
  ("remote-shell" "/bin/sh")
  ("stat" "\\stat")
  ("file-exists" "test -e")
  ("id" "/usr/bin/id")
  ("gid-string" "my-user")
  ("ls" "/bin/ls --color=never")
  ("ls-dired" t)
  ("gid-integer" 1016)
  ("readlink" "\\readlink")
  ("perl-file-spec" t)
  ("perl-cwd-realpath" t)
  ("perl" "\\perl")))

Answer 1

I believe I understand. Your files-dir is contained in load-path. When Tramp is loaded, Emacs finds the file tramp in this directory and tries to load it instead of tramp.el in its original directory.

Give that file another name but tramp or tramp.el, or locate it in another directory, which is not covered by load-path.