cgred does not always confine processes according to cgroups rules

Issue

Three control groups have been defined. Let's call them 'A', 'B' and 'others'. Depending on their owner, processes are confined in groups 'A' or 'B'. The rest is confined in 'others'.
If processes are started in a quick sequence, some processes that should be confined in either 'A' or 'B', end up in 'others'.