MRG: adjust Signature::name() to return Option<String> instead of filename() and md5sum()
#6016
| Job | Run time |
|---|---|
| 9m 21s | |
| 20m 21s | |
| 10m 20s | |
| 14m 39s | |
| 7m 24s | |
| 6m 0s | |
| 1h 8m 5s |