Backup files are silently ignored when using certain archive types

[Christoph Michelbach]

Depending on the kind of archive you create using file-roller, backup files (files with a `~` on the end of their names) are included or ignored. The user doesn't see any warning at all and will probably only discover this when they try to extract the archive.

# How to reproduce the symptom.
(I'm assuming you're using Nautilus with file-roller integration.)
Create a folder `testFolder` (or any name but I'll use this one to refer to it) and create a file called `testFile~` in it. Then move to the parent folder of `testFolder`. Right-click test folder and choose "Compress".
## Correct behavior.
Choose `.7z` as the archive format making it a 7zip archive and click "Create". The archive will contain the folder `testFolder` and in it the file `testFile~`.
## Incorrect behavior.
Choose `.tar` as the archive format making it a tarball and click "Create". The tarball will contain the folder `testFolder` but it will be empty.

Note that this isn't the fault of `tar`. If you create the tarball from the command line using the command `tar`, `testFile~` will be included.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Oleg Moiseichuk (berroll)]

I met with the same issue in 16.04.1 (amd64). Tested several 'tar' archives (namely tar.7z and tar.gz) - none of them stored backup files. Maybe some problem with generation of the lists of files for archiving? '7z' and 'zip' archives do save backup files, but it seems that they rely on 'p7zip-full' package which provides 7-Zip backend for the File Roller. Until I installed this package 'zip' archives were also losing backup files.
In my older system which is 12.04LTS (i386) all the mentioned archive types properly store backup files.

[Mantas Kriaučiūnas (mantas)]

File-roller developers decided do not add files with a `~` on the end of their names to new archive in version 2.23.4 , see https://gitlab.gnome.org/GNOME/file-roller/-/blob/master/NEWS#L3858 :

        New features and user visible changes:
[...]

 * Do not add the backup files, that is files ending with ~, to the archive.

It seems we should report this issue to the upstream: https://gitlab.gnome.org/GNOME/file-roller/-/issues