Add a test for what happens with concurent calls to waitpid
Ruby 3.1 and 3.2 have a bug in their implementation, for which I'm backporting a fix. However, the current development branch doesn't have the issue (because the MJIT -> RJIT change refactored how waitpid worked substantially). I do however want to commit the test which verifies that waitpid works properly on master.
Add a test for what happens with concurent calls to waitpid
Ruby 3.1 and 3.2 have a bug in their implementation, for which I'm
backporting a fix. However, the current development branch doesn't have
the issue (because the MJIT -> RJIT change refactored how waitpid worked
substantially). I do however want to commit the test which verifies
that waitpid works properly on master.
[Fixes #19387]