Use ._is_mutable() to account for parent state proxy
#2303
| Job | Run time |
|---|---|
| 10m 5s | |
| 28s | |
| 39s | |
| 14m 58s | |
| 1m 23s | |
| 15m 1s | |
| 1m 11s | |
| 14m 3s | |
| 12m 15s | |
| 12m 32s | |
| 10m 8s | |
| 9m 49s | |
| 21m 0s | |
| 19m 50s | |
| 19m 49s | |
| 16m 10s | |
| 9m 16s | |
| 9m 18s | |
| 9m 41s | |
| 3h 27m 36s |