MRG: adjust Signature::name() to return Option<String> instead of filename() and md5sum()
#6017
| Job | Run time |
|---|---|
| 10m 14s | |
| 19m 47s | |
| 9m 24s | |
| 9m 45s | |
| 16m 15s | |
| 7m 2s | |
| 1h 12m 27s |