fails:Kernel#fork returns status zero
fails:Kernel#fork returns status non-zero
fails:Kernel#fork returns nil for the child process
fails:Kernel#fork runs a block in a child process
fails:Kernel#fork marks threads from the parent as killed
fails:Kernel.fork returns status zero
fails:Kernel.fork returns status non-zero
fails:Kernel.fork returns nil for the child process
fails:Kernel.fork runs a block in a child process
fails:Kernel.fork marks threads from the parent as killed
