Occasional issue with conditionvariable specs

[herwinw]

Example: https://github.com/natalie-lang/natalie/actions/runs/8569056088/job/23484139786

 FAIL ruby/spec::spec/core/conditionvariable/signal_spec.rb#test_0001_passes all specs (2901.91s)
        Expected #<Process::Status: pid 18873 exit 1> to be success?.
        /natalie/test/ruby/ruby_specs_test.rb:35:in `block (4 levels) in <top (required)>'

Once in a while this spec fails. Most times a retry resolves this issue, but it would be nice to not have this issue in the first place.