fix handling of **nil with named block #399
| Job | Run time | 
|---|---|
| 42s | |
| 38s | |
| 40s | |
| 40s | |
| 46s | |
| 40s | |
| 44s | |
| 37s | |
| 1m 23s | |
| 2m 9s | |
| 29s | |
| 1m 6s | |
| 32s | |
| 1m 3s | |
| 1m 26s | |
| 1m 7s | |
| 1m 35s | |
| 1m 7s | |
| 1m 2s | |
| 1m 27s | |
| 1m 8s | |
| 21m 1s | 
| Job | Run time | 
|---|---|
| 42s | |
| 38s | |
| 40s | |
| 40s | |
| 46s | |
| 40s | |
| 44s | |
| 37s | |
| 1m 23s | |
| 2m 9s | |
| 29s | |
| 1m 6s | |
| 32s | |
| 1m 3s | |
| 1m 26s | |
| 1m 7s | |
| 1m 35s | |
| 1m 7s | |
| 1m 2s | |
| 1m 27s | |
| 1m 8s | |
| 21m 1s |