which has been fixed (better: worked around) in Impish but the workaround has not been backported. This is likely not a bug in backuppc, my impression is that for some reason the armhf autopkgtest testbed images are lacking the suid bit on ping6. Reinstalling the package sets it, and the the tests pass.
The two regressions are not due to this SRU but due to:
https:/ /bugs.launchpad .net/ubuntu/ +source/ backuppc/ +bug/1936437
which has been fixed (better: worked around) in Impish but the workaround has not been backported. This is likely not a bug in backuppc, my impression is that for some reason the armhf autopkgtest testbed images are lacking the suid bit on ping6. Reinstalling the package sets it, and the the tests pass.