bug#18141: 24.4.50; saving .gz file breaks file coding

[Stefan Monnier]

> Ctrl-C is safe with any correctly written software.

Agreed.

> It's more than 5 times as fast, thus very relevant.

Agreed (I also use C-c on a regular basis to exit Emacs).

> 1 GB costs 0.10 EUR per month, and I don't want to waste several
> dozens of GB of backups (easily produced without clean-up). Once
> becoming useless, backup files have no value.

Note that in this specific case, the problem only happens if you ask
Emacs to keep backups.  I have set make-backup-files to nil many years
ago and never looked back (all the files where it might matter are under
some kind of VCS anyway).

>> After r111638, the prompt is issued before backing up the file.
> And that's a much more logical sequence.

Indeed.  The problem is that this is done by changing the moment at
which the coding-system is chosen (and makes it "too early") instead of
changing the moment at which the backup is made (which is the right
thing to do, but requires more significant changes in the code).


        Stefan