Reproducible in MediaWiki-Vagrant:
```
user@machine:/mediawiki/vagrant$ vagrant ssh
vagrant@vagrant:~$ node -v
v6.13.1
vagrant@vagrant:~$ npm -v
2.15.12
vagrant@vagrant:~$ cd /vagrant/mediawiki
vagrant@vagrant:/vagrant/mediawiki$ rm -rf node_modules/
vagrant@vagrant:/vagrant/mediawiki$ npm install
...
vagrant@vagrant:/vagrant/mediawiki$ xvfb-run npm run selenium
...
[chrome #0-0] Spec: /vagrant/mediawiki/tests/selenium/specs/page.js
[chrome #0-0] Running: chrome
[chrome #0-0]
[chrome #0-0] Page
[chrome #0-0]
[chrome #0-0] Page
[chrome #0-0] ✓ should be creatable
[chrome #0-0] 1) should be re-creatable
[chrome #0-0] 2) should have history
[chrome #0-0]
[chrome #0-0]
[chrome #0-0] 1 passing (12s)
[chrome #0-0] 5 failing
[chrome #0-0]
[chrome #0-0] 1) Page should be re-creatable:
[chrome #0-0] Cannot find module 'bluebird'
...
Warning: Task "webdriver:test" failed. Use --force to continue.
Aborted due to warnings.
```
Not reproducible on my desktop machine, probably because it has a newer npm version:
```
$ node -v
v9.9.0
$ npm -v
5.8.0
$ rm -rf node_modules/
$ npm install
...
$ npm run selenium
...
(no errors)
```