builtin/gc: fix crash when running git maintenance start
#5183
| Job | Run time |
|---|---|
| 4s | |
| 35s | |
| 4m 48s | |
| 3m 15s | |
| 9m 21s | |
| 7m 31s | |
| 1m 52s | |
| 3m 59s | |
| 3m 28s | |
| 4m 23s | |
| 3m 54s | |
| 9m 56s | |
| 14m 30s | |
| 10m 18s | |
| 14m 27s | |
| 10m 34s | |
| 14m 28s | |
| 10m 2s | |
| 10m 16s | |
| 14m 41s | |
| 14m 14s | |
| 12m 35s | |
| 9m 24s | |
| 6m 47s | |
| 5m 14s | |
| 5m 30s | |
| 5m 57s | |
| 7m 27s | |
| 5m 1s | |
| 5m 56s | |
| 7m 16s | |
| 8m 26s | |
| 9m 29s | |
| 7m 5s | |
| 5m 34s | |
| 6m 6s | |
| 6m 36s | |
| 8m 13s | |
| 5m 17s | |
| 6m 11s | |
| 7m 25s | |
| 5m 45s | |
| 5h 13m 50s |