revert change of 926510f. Instead allow set_default_io_service to take nullptr. In order to safely fork, call set_default_io_service(nullptr) to make sure the io_service destructor is called and all underlying threads joined.
revert change of 926510f. Instead allow set_default_io_service to take nullptr. In order to safely fork, call set_default_io_service(nullptr) to make sure the io_service destructor is called and all underlying threads joined.

Cylix/tacopie,Cylix/tacopie,Cylix/tacopie