Hitting "can't modify frozen String" when passing `jenkins_path` as an ENV variable.

[atmosx]

Hi,

When I use the following code to set jenkins_path:

def jenkins_path
  ENV['JENKINS_PATH'] || '/'
end
[...]
client = JenkinsApi::Client.new(jenkins_path: jenkins_path)

Calling the handler fails with can't modify frozen String because of gsub!. If I pass the path as a string ('/jenkins') when creating the client object works as expected.