NameError in waitable.rb

[igorpeshansky]

Version 1.3.2 crashes with:

2018-07-22 15:56:06 +0000 [error]: unexpected error error_class=NameError error=#<NameError: undefined local variable or method `rc' for #<Systemd::Journal:0x0000000004494bf8>>
  2018-07-22 15:56:06 +0000 [error]: /opt/google-fluentd/embedded/lib/ruby/gems/2.4.0/gems/systemd-journal-1.3.2/lib/systemd/journal/waitable.rb:64:in `file_descriptor'
  2018-07-22 15:56:06 +0000 [error]: /opt/google-fluentd/embedded/lib/ruby/gems/2.4.0/gems/systemd-journal-1.3.2/lib/systemd/journal.rb:55:in `initialize'
  2018-07-22 15:56:06 +0000 [error]: /opt/google-fluentd/embedded/lib/ruby/gems/2.4.0/gems/fluent-plugin-systemd-0.0.9/lib/fluent/plugin/in_systemd.rb:38:in `new'
  2018-07-22 15:56:06 +0000 [error]: /opt/google-fluentd/embedded/lib/ruby/gems/2.4.0/gems/fluent-plugin-systemd-0.0.9/lib/fluent/plugin/in_systemd.rb:38:in `init_journal'
  2018-07-22 15:56:06 +0000 [error]: /opt/google-fluentd/embedded/lib/ruby/gems/2.4.0/gems/fluent-plugin-systemd-0.0.9/lib/fluent/plugin/in_systemd.rb:86:in `watch'
  2018-07-22 15:56:06 +0000 [error]: /opt/google-fluentd/embedded/lib/ruby/gems/2.4.0/gems/fluent-plugin-systemd-0.0.9/lib/fluent/plugin/in_systemd.rb:70:in `run'