bug#36859: Customizable fit-window-to-buffer

[Juri Linkov <juri@linkov.net>]

>> The only practicable solution IMHO is to provide a plain
>> 'vc-adjust-window-size-function' option defaulting to
>> 'shrink-window-if-larger-than-buffer' and allowing 'ignore' and
>> 'fit-window-to-buffer' as alternatives.
>
> This looks like hooks.  I too like hooks, I don't understand
> why vc uses such inconvenient macros as vc-run-delayed
> instead of more flexible hooks.  Window management could use
> hooks more often, e.g. to delay setting window-start/window-point
> to later times when the buffer is ready, etc.

I see there is a hook already in vc: 'vc-post-command-functions'.
But it's unclear how to use it to call 'shrink-window-if-larger-than-buffer'
from the hook only on vc-log and vc-diff commands.

Maybe vc-log-internal-common and vc-diff-internal could provide new hooks,
e.g. vc-log-post-command-functions and vc-diff-post-command-functions.