MRG: adjust Signature::name() to return Option<String> instead of filename() and md5sum()
#6014
| Job | Run time |
|---|---|
| 9m 12s | |
| 10m 42s | |
| 20m 32s | |
| 6m 57s | |
| 8m 26s | |
| 17m 8s | |
| 1h 12m 57s |