fixes #469 assertion failure in ipc_shutdown (really)
fixes #469 assertion failure in ipc_shutdown (really)

JackDunaway/featherweight-nanomsg,zerotacg/nanomsg,yan97ao/nanomsg,wirebirdlabs/featherweight-nanomsg,wirebirdlabs/featherweight-nanomsg,thisco-de/nanomsg,reqshark/nanomsg,snikulov/nanomsg,zerotacg/nanomsg,wirebirdlabs/featherweight-nanomsg,reqshark/nanomsg,snikulov/nanomsg,thisco-de/nanomsg,featherweight/ftw-kernel-nanomsg,yan97ao/nanomsg,JackDunaway/featherweight-nanomsg,featherweight/ftw-kernel-nanomsg,zerotacg/nanomsg,imp/nanomsg,imp/nanomsg,JackDunaway/featherweight-nanomsg,yan97ao/nanomsg,reqshark/nanomsg,imp/nanomsg