Setting IPv6 to manual on a bridge connection and restarting NetworkManager always creates and uses a new bridge
I tried to set a manual v6 address on a bridge, entered the address, prefix, gateway, DNS (space-separated) and search domains (space separated). All is fine after saving it. However, due to the bridge not showing in the drop-down (only Auto Ethernet, and knowing from previous experiences that if I clicked that it would stop using the bridge and use the phsical interface directly) I opted to do a service NetworkManager restart. (I've also been doing this to renew the bridge leases before, as there is no way in the menu to do this).
On restart, the old bridge is no longer used (last used isn't "now"), but there is a completely new "bridge0" interface with some bogus configuration values. Both v4 and v6 are back at automatic, and there are previously unset "Additional DNS servers" and "search domains" set, obviously taken from the DHCP-assigned addresses.
I now have 3 bridges, two named "bridge0" and one "Bridge connection 1", only the latest of which is used, and at a loss as to how to configure a manual v6 address.
OS: Ubuntu 16.04 NM: 1.2.6-0ubuntu0.16.04.3