TravisCI is failing on node <6

[naganowl]

Expected behaviour

#2752 and #2747 only pass Travis for node 6.

Actual behaviour

They should pass on npm 6

Environment Details

The PRs are failing on validation of the commit message on older versions of npm, but succeeds on npm 6. The error message it outputs is

0.77s$ npm run init
0.09s$ if [ "$VALIDATE_COMMIT_MSG" == "true" ]; then npm run travis; else ./scripts/validate-commit-msg.sh $TRAVIS_COMMIT; fi
INVALID COMMIT MSG: does not match "<type>(<scope>): <subject>" !
/home/travis/build/karma-runner/karma/.git/COMMIT_EDITMSG
The command "if [ "$VALIDATE_COMMIT_MSG" == "true" ]; then npm run travis; else ./scripts/validate-commit-msg.sh $TRAVIS_COMMIT; fi" failed and exited with 1 during .

Steps to reproduce the behaviour

1. https://travis-ci.org/karma-runner/karma/jobs/248146863
2. https://travis-ci.org/karma-runner/karma/builds/244545086

[chrahunt]

The validation is not succeeding on 6, it is just not being done (since $VALIDATE_COMMIT_MSG is set to true).