Pirania malformed auth_macs file

We ended up with /tmp/pirania/read_for_access/auth_macs having this content:

```
56:7b:aa:35:69:ce1820 122580
ee:7e:0a:28:e4:8c4347 122580
7e:76:d4:da:3e:c86874 122580
aa:f7:e9:84:86:6e 466910
22:a2:b8:9f:12:5a 460166
5a:9d:6d:64:37:da 467203
```
`56:7b:aa:35:69:ce`, `ee:7e:0a:28:e4:8c` and `7e:76:d4:da:3e:c8` are the actual macs.

I have no clue on how we got there. 