jruby 9.1.9.0-SNAPSHOT (2.3.3) 2017-04-28 038f790 OpenJDK 64-Bit Server VM 25.121-b14 on 1.8.0_121-b14 +jit [linux-x86_64]

Which can be reproduced with:

 bin/jruby spec/mspec/bin/mspec run -Gfails -Gcritical -Gslow spec/ruby/language/break_spec.rb

This specific spec is currently excluded in jruby.2.3.mspec so that's why it got unnoticed.
There are only 3 ruby_exe calls in that spec so once this is fixed I would advise to include it on CI.