fails to capture executable in local node_modules dir (?) about node-which HOT 1 CLOSED

$ cat package.json
{
  "name": "which-node-modules-bin",
  "version": "1.0.0",
  "scripts": {
    "test": "node test.js",
    "path": "echo $PATH"
  },
  "dependencies": {
    "istanbul": "^0.4.5",
    "which": "^1.2.12"
  }
}

$ cat test.js
const which = require('which');
var resolved = which.sync('istanbul');

console.log(resolved);

$ npm test

> [email protected] test /Users/isaacs/dev/js/x/which-node-modules-bin
> node test.js

/Users/isaacs/dev/js/x/which-node-modules-bin/node_modules/.bin/istanbul

$ node test.js
/Users/isaacs/dev/js/x/which-node-modules-bin/node_modules/which/which.js:131
  throw getNotFoundError(cmd)
  ^

Error: not found: istanbul
    at getNotFoundError (/Users/isaacs/dev/js/x/which-node-modules-bin/node_modules/which/which.js:13:12)
    at Function.whichSync [as sync] (/Users/isaacs/dev/js/x/which-node-modules-bin/node_modules/which/which.js:131:9)
    at Object.<anonymous> (/Users/isaacs/dev/js/x/which-node-modules-bin/test.js:2:22)
    at Module._compile (module.js:556:32)
    at Object.Module._extensions..js (module.js:565:10)
    at Module.load (module.js:473:32)
    at tryModuleLoad (module.js:432:12)
    at Function.Module._load (module.js:424:3)
    at Module.runMain (module.js:590:10)
    at run (bootstrap_node.js:394:7)

$ npm run path

> [email protected] path /Users/isaacs/dev/js/x/which-node-modules-bin
> echo $PATH

/Users/isaacs/dev/npm/npm/bin/node-gyp-bin:/Users/isaacs/dev/js/x/which-node-modules-bin/node_modules/.bin:/Users/isaacs/.basher/cellar/bin:/Users/isaacs/bin:/Users/isaacs/.rvm/bin:/Users/isaacs/.basher/bin:/Users/isaacs/bin:/usr/local/bin:/usr/local/sbin:/usr/local/include:/usr/bin:/usr/sbin:/usr/libexec:/bin:/sbin

$ echo $PATH
/Users/isaacs/.basher/cellar/bin:/Users/isaacs/bin:/Users/isaacs/.rvm/bin:/Users/isaacs/.basher/bin:/Users/isaacs/bin:/usr/local/bin:/usr/local/sbin:/usr/local/include:/usr/bin:/usr/sbin:/usr/libexec:/bin:/sbin