NetworkManager should work correctly in face of pruning /etc or /var.
That is for example relevant in the context of factory reset and stateless systems (e.g. systemd). But it is desirable in general.

That means:

- NM should be happy starting with no files in /etc or /var. If it
  needs some missing files or directories, it should create them as needed.
  Even better: not requiring any files in the first place. Missing configuration
  should be (silently) accepted and compile time defaults apply.
  One thing that comes in mind is that currently we don't have a compile time 
  default for main.plugins setting (although we enable plugins at compile
  time). See bug 738611 for a patch.
  
- ensure that we properly split between configuration, state and resources.
  
  One issue that comes to mind are files like
  /etc/NetworkManager/VPN/nm-*-service.name .
  In fact, these files are not really user configuration, but configuration of 
  the NM installation. It shouldn't be in /etc in the first place. Instead we
  should install these files to /usr/lib/NetworkManager/VPN/* or similar.
  To provide backward compatibility however, NM should accept files 
  /etc/NetworkManager/VPN/X to shaddow the corresponding
  /usr/lib/NetworkManager/VPN/X file. 
  Although these files are not user-configuration, this gives the user a 
  possibility to overwrite the configuration without changing the files in
  /usr. If the user wants to remove a plugin, removing the files from /etc
  will no longer work as it does now. That seems non-intuitive, but again, the 
  user isn't really expected to edit these files. The user should instead 
  uninstall the plugin. We should accept an empty file as "file does not
  exist".
  Note, that also nm-applet reads these files (search: VPN_NAME_FILES_DIR).
  Actually, new VPN plugin packages should install the same file under both
  /etc and /usr/lib. That gives us compatibility towards older nm-applet/NM 
  while still supporting the scenario of clearing /etc (maybe we should add a 
  comment '# this file shaddows /usr/lib/NetworkManager/VPN/X').

  The VPN plugin files are just an example.
  TODO: check, if the same applies in other cases.