bug#50431: revert-buffer doesn't preserve read-onlyness

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> > Hm, yes.  Reverting a buffer disables all the minor modes?
>> 
>> Maybe minor modes should be restored after reverting?

I'm not sure how useful that'd be in general.  view-mode is slightly
special here because people use that selectively with the intent of "I'm
not really editing this one file", though.

> Only the minor modes that are automatically turned on when visiting
> the file.  Reverting should produce the same effect as killing the
> buffer and then visiting the file anew, nothing more, nothing less.
>
> For that reason, I'm not sure the change that preserves the read-only
> status across reverts is correct.  At the very least, it should be an
> opt-in feature, IMO.

If a user has made an explicit readedness choice for a buffer, then
preserving that over a revert is probably what they want.  (Especially
with auto-reverting.)  But if we get complaints, we can add a user
option.