yamllint is broken on master because it also runs on vendor and node_modules directories and some upstream modules contain example files that don't lint (by design).
https://integration.wikimedia.org/ci/job/integration-jenkins-yamllint/149/console
```
23:52:35 + /srv/deployment/integration/slave-scripts/tools/yamllint.py /srv/ssd/jenkins-slave/workspace/integration-jenkins-yamllint
23:52:35 ERROR Invalid file /srv/ssd/jenkins-slave/workspace/integration-jenkins-yamllint/tools/node_modules/grunt/node_modules/js-yaml/examples/custom_types.yaml raised: could not determine a constructor for the tag '!space'
23:52:35 in "/srv/ssd/jenkins-slave/workspace/integration-jenkins-yamllint/tools/node_modules/grunt/node_modules/js-yaml/examples/custom_types.yaml", line 3, column 3
```
We need a way to exclude directories and files. Or alternatively, switch to something like Grunt with a yamllint task and run it with a whitelist file pattern (like for jscs).