Setting nix.settings.sandbox-paths replaces Nix compiled sandbox defaults. Keeping only /dev/net made local builds lose the sandbox shell that normally provides /bin/sh, which broke upstream scripts with /bin/sh shebangs in packages such as X11-fonts and openldap.
Use extra-sandbox-paths for /dev/net instead. This keeps Nix daemon defaults intact, including the configured sandbox shell, while still allowing builds that need /dev/net.
Add eval coverage for both Linux output sets so future changes keep /dev/net in extra-sandbox-paths and do not reintroduce an explicit sandbox-paths override.
Ryan Yin