I am using the emacs master build version (25.1.50.x).

Here is how I set my minor mode map:

=====
(defvar modi-mode-special-map (make-sparse-keymap)
  "Special keymap for `modi-mode' whose bindings begin with
`modi-special-keymap-prefix'.")
(fset 'modi-mode-special-map modi-mode-special-map)

(defvar modi-mode-map (let ((map (make-sparse-keymap)))
                        (define-key map modi-special-keymap-prefix
'modi-mode-special-map)
                        map)
  "Keymap for `modi-mode'.")

;; The keymaps in `emulation-mode-map-alists' take precedence over
;; `minor-mode-map-alist'
(add-to-list 'emulation-mode-map-alists `((modi-mode . ,modi-mode-map)))
=====

Also there was a typo in my previous email:

I meant:

=====
The strange thing is that

(string-match "." nil) ; *not* (string-match-p ..)

generates proper backtrace as expected ..
=====

On Mon, Jul 11, 2016 at 11:28 AM Stefan Monnier <monnier@iro.umontreal.ca>
wrote:

> The overriding-local-map if non-nil disables all other maps.
> And in Emacs<24.4, the same holds for overriding-terminal-local-map.
>
> Could it be you're using a package written for Emacs>=24.4 which sets
> a sparse keymap in overriding-terminal-local-map to just override a few
> key bindings, but you use it with Emacs<24.4 where that ends up
> disabling all other bindings?

-- 

-- 
Kaushal Modi