bug#38992: 27.0.60; when enabled, fido-mode seems to break vc-git-grep

[Dmitry Gutov]

On 24.01.2020 17:11, Stefan Monnier wrote:
> It's arguably breaking compatibility.  But you might be right that maybe
> it's a non issue.  A quick `grep` shows that outside Emacs itself, at
> least Helm might be affected

Speaking of Helm, there are only a few matches:

https://github.com/emacs-helm/helm/search?q=minibuffer-completion-confirm&unscoped_q=minibuffer-completion-confirm

And AFAICT it also binds minibuffer-completion-confirm to either t 
straight away or to the value of the must-match argument (as opposed to 
its reverse as we might expect).

And here's some documentation of that usage: 
https://github.com/emacs-helm/helm/blob/75563d35a6ae62c669aba4b7bf02ed23b13f6de4/helm.el#L5617-L5623

Overall, it seems like it uses its variable for its own purpose (later 
comparing the value to t in a different function, for example), and it 
could just as well created a global variable solely for use in Helm. So 
it shouldn't be affected by the proposed changes.

With that said, Eli, what do you think about the two patches I've sent 
to this bug earlier? I'd like them in emacs-27.