Test failure: expect(@result_3).to_not eq(true)

[utkarsh2102]

Hello,

Whilst trying to build this library from source, we hit a random test failure:

Relevant part (hopefully):
>      Failure/Error: expect(@result_3).to_not eq(true)
> 
>        expected: value != true
>             got: true
> 
>        (compared using ==)
>      # ./spec/in-paralell_spec.rb:137:in `block (2 levels) in <top (required)>'
> 
> Finished in 9.92 seconds (files took 0.10551 seconds to load)
> 19 examples, 1 failure
> 
> Failed examples:
> 
> rspec ./spec/in-paralell_spec.rb:130 # .run_in_parallel should raise an exception and return immediately with kill_all_on_error and one of the processes errors.
> 
> /usr/bin/ruby2.7 -I/usr/share/rubygems-integration/all/gems/rspec-support-3.9.3/lib:/usr/share/rubygems-integration/all/gems/rspec-core-3.9.2/lib /usr/share/rubygems-integration/all/gems/rspec-core-3.9.2/exe/rspec --pattern ./spec/\*\*/\*_spec.rb --format documentation failed
> ERROR: Test "ruby2.7" failed: 

The full build log is available from:
http://qa-logs.debian.net/2021/01/20/ruby-in-parallel_0.1.17-1.2_unstable.log

---

Me and Sebastian discussed this more here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=980585

As for us, we couldn't really reproduce it. But on some machines, it fails like this. And since it's not really reproducible for us, we couldn't debug it further and hence asking for help.

In case you have any idea what's causing this, it'd be really helpful.

Thanks in advance! :)
CC: @puppetlabs-jenkins