bug#21559: 25.0.50; auto-revert-mode breaks git rebase

[Michael Albinus]

Dmitry Gutov <dgutov@yandex.ru> writes:

Hi Dmitry,

> From what I see of this switch's description, it's going to (slightly?
> imperceptibly?) slow down the VC operations. It would be cool to see
> some measurement of that effect.
>
> Failing that, why don't we try something else first? If the problem
> occurs solely due to auto-revert-mode's calls to Git, let's try adding
> that environment variable binding inside auto-revert-handler. The
> patch is below. Does it solve the problem as well?

I'm not so happy seeing git specific code in autorevert.el (yes, I know,
it's just an environment variable). All git specifics shall be kept in
vc-git.el. Otherwise, we would go into a dependency nightmare, soon. Do
you know, that magit would like to see this setting?

If this variable hurts for standard operation of vc-git, we could set it
depending whether (auto)revert is running, or not. There is the variable
`revert-buffer-in-progress-p', which is non-nil if reverting is in
progress. I could set it also before calling `vc-refresh-state' in
`auto-revert-handler'. And in vc-git.el, `process-environment' could be
extended or not, depending on the value of `revert-buffer-in-progress-p'.

Best regards, Michael.