Motivation for this change

Exhibitor wants to change its local file and therefor in preInstall phase all files are copied from /nix/store to /var folder. However since starting zookeeper shell scripts are wrapped by nix (especially zkServer.sh after 6e9c7f0#diff-f80d089d8c5ac8a5901041c8810cb128) exhibitor still starts from the /nix/store, tries to modify files there and fails.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Fits CONTRIBUTING.md.
• Tested on NixOS box by running the updated service and validating that it's working as expected