Github user StevenLangbroek commented on the issue:
https://github.com/apache/flink/pull/5395
[Ruby 2.0.0 support
status](https://www.ruby-lang.org/en/news/2016/02/24/support-plan-of-ruby-2-0-0-and-2-1/)
> As it has been announced before, all support for Ruby 2.0.0 has ended
today *(note: february 2016)*. Bug and security fixes from more recent Ruby
versions will no longer be backported to 2.0.0, and no further patch release of
2.0.0 will be released.
Running old software is always a security risk.
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