No warnings about misconfiguration

[frederictobiasc]

Hi!
I understand we cannot prevent users completely of creating invalid configurations. But consider the following case:

If preservation is configured to preserve a directory (say /etc/foo) that is part of a path managed by etc.environment (say etc.environment."foo/bar") this has potentially unintended results.

It's also a bit tricky, since configuration for etc.environment could be provided by any module (e.g. from nixpkgs) rather than being defined by the user creating the preservation configuration.

I think especially for etc.environment it would be nice if some kind of warning would be generated, if there is potential interference with the preservation configuration.