No ASN in output when checking invalids ROAs with as-set

[Darren O'Connor]

When checking ROAs, and the source ASN happens to have an AS-SET, bird does
not output the ASN itself.

Here is an example without an AS-SET:
$ birdc 'show route primary table master4 where roa_check(roa_v4, net,
bgp_path.last_nonaggregated) = ROA_INVALID' | grep 186.28
186.28.232.0/24      unreachable [BGP1v4 2021-02-11 from 46.30.8.72] *
(100) [AS263710i]

Here is an example with an AS-SET:
$ birdc 'show route primary table master4 where roa_check(roa_v4, net,
bgp_path.last_nonaggregated) = ROA_INVALID' | grep 185.186
185.186.206.0/24     unreachable [BGP3v4 2021-02-07 from 192.110.255.57] *
(100) [?]

The source ASN in the first shows as 263710, but the second shows none at
all.

This is the actual live prefix for the second:
bird> show route all for 185.186.206.0/24
Table master4:
185.186.206.0/24     unreachable [BGP3v4 2021-02-07 from 192.110.255.57] *
(100) [?]
        Type: BGP univ
        BGP.origin: Incomplete
        BGP.as_path: 13030 8529 28885 {206350}

As the query is specifying last_nonaggregated, I'd expect the output to
contain that ASN.

Thanks
D