This reverts commit 8dbd553792dcaf5074c47367ed6740f516862bad. The update has changed where mailman-web looks for its database and broken the Mailman module in NixOS.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at https://nixos.org/nixos and in the manual in doc/manual.