bug#21634: text-scale-adjust suggestion

[Juri Linkov]

>> Maybe a new mode transient-repeat-mode could be created.
>> Then text-scale-adjust could temporarily activate
>> this mode instead of using set-transient-map.
>
> Yeah, that's a good idea.

Another command that could use it as well is 'indent-rigidly'.
Currently it's too inconvenient to type C-g to get out of it.
Exiting after a delay would be a better option.