(QENG-969) Fix bug introduced with last patch.

Last patch addressed some PR comments regarding coding style and led to bug
which is now fixed.

Signed-off-by: Wayne <wayne@puppetlabs.com>
Merge pull request #381 from waynr/feature/qeng-969-add-modify-tk-config-dsl-method

(QENG-969) Fix bug introduced with last patch.