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

[Dmitry Gutov]

On 05.02.2020 17:27, João Távora wrote:
> With the original problem fixed, Dmitry came to what can be seen as a
> UI deficiency in fido-mode.

Not exactly. There have been several issues discussed in this report, 
and it's really a problem that the user can't easily input something 
that completing-read would allow.

A new bug report has arrived since: 
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=39407 It is now 
erroneously marked as fixed because it has been merged with this one. We 
should undo that.

The proposed workaround (using M-j) is itself problematic since it 
allows you to input whatever even when a match is required. So there are 
bug here.

> After analysing this with Stefan, we arrived
> at the conclusion that it was actually a problem in some longstanding
> minibuffer.el workings.

Not exactly. At least, icomplete-mode seems to work okay in both of 
these respects (please correct me if I'm wrong).

> Maybe, Dmitry, we could revert to the earlier proposal with the new
> variable and somehow deprecate/discourage use of the one you're
> trying to change?  That should be safe and bring all the benefits of
> your change, right?

Yes, we can do that. I'll make the new variable private, so we can rid 
of it quickly on master.