inbound IPv6 connection fails if address has zero groups in it

Inbound IPv6 BGP connections fail to match a configured peer if the configured peer address has zero groups in it.

this seems to be because the peer addresses are stored in "full" form (i.e. with "0:" for each zero group, but the google library used to get the incoming address normalizes the address to replace zero groups with "::".

I'll try to fix this myself