Sorry I don't have simple reproducible code for this either.
Here's the trace:
https://travis-ci.org/godfat/pork/jobs/107027673
The line was:
https://github.com/godfat/pork/blob/pork-1.4.4/lib/pork/test.rb#L16
You can see that in line 13 that super works, but not the one in line 16.
It used to work on jruby 9.0.4.0.
You could reproduce this by cloning the repo and run jruby -S rake test whenever dependencies were all installed.