Victoria only supports focal, so the upgrade from victoria
(starting from victoria+1) should use focal.
This patch should not be backported to victoria, because the
upgrades from ussuri still need to use bionic.
In order to make it work on focal:
- do not fail if ebtables does not contain the broute table
(which happens when it is based on nft);
- when the swift loopback image is remounted on upgrade,
do not use the nobarrier option, which was removed
with the 4.19 kernel. See also the corresponding change
in devstack: I6871a7765e3e04122d8d546f43d36bb8415383fc
Change-Id: If57c54828baf4e250ad08fdd95351490010e1b41
9c729d15fc