Comment 10 for bug 2017889

I checked (with the bgp driver) and works for me (to ping an external IP):
12:07:21.855116 tap4ffea1af-c4 M IP6 fe80::f816:3eff:fe6a:d580 > ff02::1:ff00:0: ICMP6, neighbor solicitation, who has 2001:db8::, length 32
12:07:21.855511 tap4bcf2878-b0 Out IP6 fe80::f816:3eff:fe6a:d580 > ff02::1:ff00:0: ICMP6, neighbor solicitation, who has 2001:db8::, length 32
12:07:21.855525 br-ex In IP6 fe80::f816:3eff:fe6a:d580 > ff02::1:ff00:0: ICMP6, neighbor solicitation, who has 2001:db8::, length 32
12:07:21.864405 tap4ffea1af-c4 P IP6 2001:db8::f816:3eff:fe6a:d580 > f00d:f00d:f00d:4:5054:ff:fe37:d55a: ICMP6, echo request, id 1, seq 1, length 64
12:07:21.864748 br-ex In IP6 2001:db8::f816:3eff:fe6a:d580 > f00d:f00d:f00d:4:5054:ff:fe37:d55a: ICMP6, echo request, id 1, seq 1, length 64
12:07:21.864767 enp3s0 Out IP6 2001:db8::f816:3eff:fe6a:d580 > f00d:f00d:f00d:4:5054:ff:fe37:d55a: ICMP6, echo request, id 1, seq 1, length 64
12:07:21.865370 enp3s0 In IP6 f00d:f00d:f00d:4:5054:ff:fe37:d55a > 2001:db8::f816:3eff:fe6a:d580: ICMP6, echo reply, id 1, seq 1, length 64
12:07:21.865380 br-ex Out IP6 f00d:f00d:f00d:4:5054:ff:fe37:d55a > 2001:db8::f816:3eff:fe6a:d580: ICMP6, echo reply, id 1, seq 1, length 64
12:07:21.865570 tap4ffea1af-c4 Out IP6 f00d:f00d:f00d:4:5054:ff:fe37:d55a > 2001:db8::f816:3eff:fe6a:d580: ICMP6, echo reply, id 1, seq 1, length 64

I have a (fake) ip added to br-ex though:
7: br-ex: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
    link/ether 2a:d2:6f:5b:3b:4a brd ff:ff:ff:ff:ff:ff
    inet 169.254.0.1/32 scope global br-ex
       valid_lft forever preferred_lft forever
    inet6 fd53:d91e:400:7f17::1/128 scope global
       valid_lft forever preferred_lft forever

And with this kernel flag enabled:
sudo sysctl -a | grep proxy_ndp | grep br-ex
net.ipv6.conf.br-ex.proxy_ndp = 1

How did you test it with the bgp driver?