You're welcome to change it if you want - that line is just copied from the helper Puppetlabs uses..

https://github.com/puppetlabs/puppetlabs-apache/blob/master/spec/spec_helper_acceptance.rb

https://github.com/puppetlabs/puppetlabs-postgresql/blob/master/spec/spec_helper_acceptance.rb

Beaker documentation is pretty non-existant, so difficult to know what the rationale was for it.