…ation

To quote the XDG specification:

     There is a single base directory relative to which user-specific
     data files should be written. This directory is defined by the\
     environment variable $XDG_DATA_HOME.

Rather than adding another directory to $HOME, I think that it's better
to follow this standard to avoid a cluttered home-dir.

In contrast to `.service`-units, it's not possible to declare an
`overrides.conf`, however this is done by `generateUnits` for `.nspawn`
units as well. This change breaks the build if you have two derivations
configuring one nspawn unit.

This will happen in a case like this:

``` nix
{ pkgs, ... }: {
  systemd.packages = [
    (pkgs.writeTextDir "etc/systemd/nspawn/container0.nspawn" ''
      [Files]
      Bind=/tmp
    '')
  ];
  systemd.nspawn.container0 = {
    /* ... */
  };
}
```

without this fix, binaries report their version number as "vnone"
which for example stops `image_optim` from using `advpng` (refuses
to use it not being able to tell what version number it has)

When trying to build a VM using `nixos-build-vms` with a configuration
that doesn't evaluate, an error "at `<unknown-file>`" is usually shown.

This happens since the `build-vms.nix` creates a VM-network of
NixOS-configurations that are attr-sets or functions and don't contain
any file information. This patch manually adds the `_file`-attribute to
tell the module-system which file contained broken configuration:

```
$ cat vm.nix
{ vm.invalid-option = 1; }

$ nixos-build-vms vm.nix
error: The option `invalid-option' defined in `/home/ma27/Projects/nixpkgs/vm.nix@node-vm' does not exist.
(use '--show-trace' to show detailed location information)
```

For reasons yet unknown, the vxlan backend doesn't work (at least inside
the qemu networking), so this is moved to the udp backend.

Note changing the backend apparently also changes the interface name,
it's now `flannel0`, not `flannel.1`

fixes #74941

This came in handy when I wanted to bump a patch version while avoiding
a new minor version.

…-fix

advancecomp: version number correctly embedded in binaries

rdma-core: 28.0 -> 29.0

victoriametrics: 1.34.5 -> 1.34.7

pgmetrics: 1.8.1 -> 1.9.0

ivan: add full iconset

- updateScript:
  A nix expression that can be used in passThrough to update a package

- list-git-tags:
  A shell script to list available tags in a git repository

- list-archive-two-level-versions:

  A shell script to list available versions in a web site in two
  levels: there is a page listing the available major.minor versions,
  and for each of them there is another page listings the patch level
  versions major.minor.patch.

  It is suitable for Xfce packages for instance.

How the updater works:

1. collect the available versions from the source repository (using a
script given as argument)

2. print the collected versions (for debugging)

3. (optionally) apply some transformation to the collected versions to
make them compatible with the versions used in nixpkgs (for instance,
tags in the Xfce git repository may be prefixed with the package name,
and the prefix need to be removed)

4. sort the available versions in decreasing order

5. choose the first version that pass validation:
   - check if the version may be a development version

   - if the version IS unstable, skip it and give a warning about
   skipping a development version (for debugging)

   - if the version COULD BE unstable, take it and give a warning
   about taking a potential development version (for debugging)

   - if the version IS stable, take it

6. update the package version and checksum in its nix expression

7. print the git commands for adding the modified files and for
committing the changes

It is generated by common-updater/update-script.nix

zafiro-icons: 1.0 -> 1.1

xfce: add update script

line-awesome: init at 1.3.0

nixos/build-vms: propagate file location

…14.1

linode-cli: remove deprecated perl version, init python version at 2.14.1