nixos/restic: ensure newline between backup.paths and outputs of dynamicFilesFrom

[hellodword]

Description of changes

1. Add --latest=1 for restic snapshots to minimize the output or reduce the requests (in extreme cases)
2. Add a newline after the result of concatStringsSep "\n" backup.paths to prevent it from being incorrectly concatenated with the output of the subsequent command

:b pkgs.writeScript "hello" ''
    filesFromTmpFile="$(mktemp)"
    cat ${pkgs.writeText "staticPaths" (lib.concatStringsSep "\n" ["/path/to/file1" "/path/to/file2"])} >> "$filesFromTmpFile"
    ${pkgs.writeScript "dynamicFilesFromScript" "echo /path/to/file3"} >> "$filesFromTmpFile"
    cat "$filesFromTmpFile"
''

The result is:

/path/to/file1
/path/to/file2/path/to/file3

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[robryk]

Please amend the test in nixos/tests/restic.nix so that it checks that the backup produced by remote-from-file-backup has correct contents: we actually have a test that exercises paths and dynamicFilesFrom at the same time, but that one didn't check backup's contents.

Other than that, this change seems fine.

[hellodword]

Please amend the test in nixos/tests/restic.nix so that it checks that the backup produced by remote-from-file-backup has correct contents: we actually have a test that exercises paths and dynamicFilesFrom at the same time, but that one didn't check backup's contents.

Other than that, this change seems fine.

Thanks! Added a check for it