Comment 6 for bug 1566589

In beta12 maybe, but in beta14 JUju got smarte by fixing bug 1575676 (with https://github.com/juju/juju/pull/5871). Now we detect the bridge name set on the default LXD profile and use that. I've just verified it does not occur on master tip (rev 4627592):

$ sudo dpkg-reconfigure -p medium lxd # change only the bridge name from lxdbr0 to e.g. lxdbr1
$ juju bootstrap lxd lxd --upload-tools # success!
$ juju kill-controller lxd -y

$ sudo dpkg-reconfigure -p medium lxd # change back to lxdbr0 for the bride
$ juju bootstrap lxd lxd --upload-tools # success!
$ juju kill-controller lxd -y

Similar steps are part of the linked PR above fixing the mentioned bug.