Comment 12 for bug 1703821

This is a post 2.13 fix upstream.
As mentioned by Christian it is in the backport branches, the respective merge for 2.13 is:
$ git tag --contains 28c4dcccc3a339dea8120eb59fea314bc0026b50
v2.13.3
Thereby this is fixed in E&F.

2.12:
$ git tag --contains 1ce8cd213c1f8948658818ac8a9a964755aac6d0
v2.12.3

So this would be open for Bionic (but at low prio since the change can be done as a user:
$ echo "unix (receive, send) type=stream peer=(label=dovecot)," >> /etc/apparmor.d/local/usr.lib.dovecot.anvil
$ echo "unix (receive, send) type=stream peer=(label=/usr/lib/dovecot/anvil)," >> /etc/apparmor.d/local/usr.sbin.dovecot