Comment 2 for bug 1309025

StacktraceTop:
 cgmanager_list_children_sync (parent=parent@entry=0x0, proxy=0x0, controller=controller@entry=0x426d47 "systemd", cgroup=cgroup@entry=0x9d3e51 "user/1000.user/c2.session", output=output@entry=0x7ffffff78078) at cgmanager-client.c:6323
 cgm_list_children (controller=0x426d47 "systemd", cgroup_path=0x9d3e51 "user/1000.user/c2.session", cgroup_path@entry=0x9d3e50 "/user/1000.user/c2.session", children=children@entry=0x7ffffff78078) at ../src/shared/cgmanager.c:194
 cg_trim (controller=controller@entry=0x425c0a "name=systemd", path=0x9d3e50 "/user/1000.user/c2.session", delete_root=delete_root@entry=false) at ../src/shared/cgroup-util.c:750
 session_terminate_cgroup (s=0x9e3740) at ../src/login/logind-session.c:625
 session_stop (s=s@entry=0x9e3740) at ../src/login/logind-session.c:709