When I use an absolute url to require a module its loading strategy is propagated and the .js is not added to the module relative and a 404 occurs. I would expect the resolution rules to stop at the initial module and not cascade further, this means you cannot use relative URLs within a module required in an absolute sense.
GET http://localhost:3000/some/module/relative 404 (Not Found) require.js:1880 Uncaught Error: Script error for: /some/module/./relative http://requirejs.org/docs/errors.html#scripterror