This solves an issue, where loading the nixos-unstable module in
nixos-stable using `disabledModules` and `imports` resulted in the
following Caddyfile:
```
<globalConfig>
<vhosts>
<extraConfig>
```
instead of
```
<globalConfig>
<extraConfig>
<vhosts>
```
This is important in cases where `cfg.extraConfig` contains so called
Caddyfile snippets.
See https://caddyserver.com/docs/caddyfile/concepts#structure
Co-authored-by: Lin Jian <me@linj.tech>
fcdcccaed6