[tor-relays] why are some exit IPs missing from Exit IP DB?

[starlight.2015q3 at binnacle.cx]

At 13:29 10/8/2015 -0400, starlight.2015q3 at binnacle.cx wrote:
>Occasionally I run into a relay such as
>
>Bywadu 5A0DE94C95E2276B4BAC974A7D8FC6463C4FE8A4
>OR ip 178.33.157.6
>exit ip 31.7.58.37
>
>Where the egress/exit IP source address is
>not found in the Exit DB, shows up negative
>on ExoneraTor.  TorCheck complains. . .

Is it perhaps because the exit policy
for the above and similar relays does
not contain a "reject" line for the
alternate IP, as in

reject 178.33.157.6:*   # present
reject 31.7.58.37:*     # missing

The OR-address "reject" is automatic
and I'm guessing that if one uses
OutboundBindAddress in the config that
would also be included.

But if 'torrc' does not contain the
alternate interface IP(s) does the
'tor' daemon recognize alternate
egress source interfaces or does
one have to configure the "reject"
lines manually?

Have not come across any documentation
on this.  Would it be considered a
bug in the Tor daemon that it does
not gather multi-home source IPs
for "reject" in the exit policy?

If a relay is missing an egress IP
"reject" line and has no contact,
would that be a serious misconfiguration
that indicates BadExit should be
assigned?