NixOS/nixpkgs — pull request #5441 by nbp (2014-12-22 21:41:31+00:00)
Title: modules: Extract mkAliasDefinition from the rename.nix NixOS module.

(see code comment)
Add mkAliasDefinition, which is a convenient property used to transfer all definitions and their properties from one option to another. This property is useful for renaming options, and also for including properties from another module system, including sub-modules.

cc @offlinehacker