How would this then be solved? Letting the .dockerinit process handle this? And to be honest - the problem is exaggerated and not worth fixing on Docker level.

How would this then be solved? Letting the .dockerinit process handle this? And to be honest - the problem is exaggerated and not worth fixing on Docker level. Programs launching child processes have to handle SIGCHLD properly anyway - PID 1 or not. This is only a problem with badly written software.