MRG: adjust Signature::name() to return Option<String> instead of filename() and md5sum()
#7642
| Job | Run time |
|---|---|
| 11m 16s | |
| 10m 6s | |
| 10m 51s | |
| 6m 22s | |
| 6m 2s | |
| 7m 5s | |
| 51m 42s |