In org-eldoc.el, org-eldoc-get-mode-local-documentation-function function,
there is this code:
(setq doc-func (and eldoc-documentation-function
(puthash lang doc-func org-eldoc-local-functions-cache))
Unfortunately, this code does not work for shell-mode.
Especially, if you get a temp buffer and try to turn it into shell mode,
you get an error because there is no associated process.
Emacs 25.1 uses this in the shell-mode function to find which shell:
(let ((shell (file-name-nondirectory (car
(process-command (get-buffer-process (current-buffer))))))
but if there is no process, get-buffer-process returns nil and
I am only reporting this because I am not sure what to do about it
But surely it is a bit annoying that
<s TAB shell
runs into error every time.