A very poor implementation of a SIGCHLD handler

apply the patch from opencontainers/runc#332

Reorder checks in Walk to avoid panics
Also added test for host PID namespace

LK4D4/runc@6c198ae

apply the patch from opencontainers/runc#332

Reorder checks in Walk to avoid panics
Also added test for host PID namespace

LK4D4/runc@6c198ae

apply the patch from opencontainers/runc#330

LK4D4/runc@6dad176

Fix nested cgroups

Fixes moby#16206

apply the patch from opencontainers/runc#330

LK4D4/runc@cd82cae

Merge pull request rancher-archives#6 from ibuildthecloud/cgroup-fix

Fix nested cgroups

A very poor implementation of a SIGCHLD handler