bug#69578: 30.0.50; tab-bar-mode binding of (control tab) not always useful

[Juri Linkov]

> tab-bar--define-keys makes bindings for TAG like this:
>
>   (unless (global-key-binding [(control tab)])
>     (global-set-key [(control tab)] #'tab-next))
>   (unless (global-key-binding [(control shift tab)])
>     (global-set-key [(control shift tab)] #'tab-previous))
>   (unless (global-key-binding [(control shift iso-lefttab)])
>     (global-set-key [(control shift iso-lefttab)] #'tab-previous))
>
> These bindings stop taking effect if a mode has its own bindings for
> control tab, for instance. A prominent example is Magit.

The developers of Org mode took courage and
replaced their C-TAB bindings with C-c C-TAB:
https://lists.gnu.org/archive/html/bug-gnu-emacs/2020-09/msg00341.html
The developers of Magit could do the same.