Comment 5 for bug 1825563

I've verified this in an lxc container using the instructions provided.

root@cosmic:~# cat /tmp/ubuntu-release-upgrader-vhkwxwud/DistUpgradeVersion.py
VERSION = '19.04.16.1'
root@cosmic:~# grep "postgresql-10" /var/log/dist-upgrade/main.log
2019-04-19 23:28:49,876 DEBUG Keep at same version: bash-completion bcache-tools bsdmainutils byobu bzip2 command-not-found command-not-found-data cpio cron dosfstools eject finalrd friendly-recovery htop iproute2 less libatm1 libbind9-160 libbz2-1.0 libdns-export1102 libdns1102 libestr0 libevent-2.1-6 libexpat1 libfastjson4 libgdbm5 libgeoip1 libgpm2 libicu60 libidn2-0 libirs160 libisc-export169 libisc169 libisccc160 libisccfg160 libksba8 liblwres160 liblzo2-2 libmnl0 libmpdec2 libnetfilter-conntrack3 libnfnetlink0 libnpth0 libntfs-3g88 libpcap0.8 libpci3 libperl5.26 libpython3.6 libpython3.6-minimal libpython3.6-stdlib libreadline5 libreadline7 librtmp1 libsepol1 libsigsegv2 libslang2 libssl1.0.0 libtasn1-6 libtext-wrapi18n-perl libusb-1.0-0 libutempter0 libx11-6 libx11-data libxau6 libxdmcp6 libxext6 libxmuu1 libxslt1.1 libyaml-0-2 linux-base lshw manpages mawk mime-support mlocate mtr-tiny pastebinit patch pciutils perl-modules-5.26 pinentry-curses pollinate popularity-contest postgresql-10 postgresql-client-10 powermgmt-base python3-asn1crypto python3-automat python3-blinker python3-certifi python3-colorama python3-commandnotfound python3-configobj python3-constantly python3-hyperlink python3-idna python3-incremental python3-jinja2 python3-json-pointer python3-jsonpatch python3-pyasn1 python3-pyasn1-modules python3-requests-unixsocket python3-serial python3-service-identity python3.6 python3.6-minimal run-one screen sensible-utils shared-mime-info ssh-import-id ssl-cert sysvinit-utils tcpdump time ubuntu-keyring xauth xfsprogs xkb-data zerofree
2019-04-19 23:29:45,113 DEBUG Keep at same version: bash-completion bcache-tools bsdmainutils byobu bzip2 command-not-found command-not-found-data cpio cron dosfstools eject finalrd friendly-recovery htop iproute2 less libatm1 libbind9-160 libbz2-1.0 libc-bin libc6 libdns-export1102 libdns1102 libestr0 libevent-2.1-6 libexpat1 libfastjson4 libgdbm5 libgeoip1 libgpm2 libicu60 libidn2-0 libirs160 libisc-export169 libisc169 libisccc160 libisccfg160 libksba8 liblwres160 liblzo2-2 libmnl0 libmpdec2 libnetfilter-conntrack3 libnfnetlink0 libnpth0 libntfs-3g88 libpcap0.8 libpci3 libperl5.26 libpython3.6 libpython3.6-minimal libpython3.6-stdlib libreadline5 libreadline7 librtmp1 libsepol1 libsigsegv2 libslang2 libssl1.0.0 libtasn1-6 libtext-wrapi18n-perl libusb-1.0-0 libutempter0 libx11-6 libx11-data libxau6 libxdmcp6 libxext6 libxmuu1 libxslt1.1 libyaml-0-2 linux-base locales lshw manpages mawk mime-support mlocate mtr-tiny pastebinit patch pciutils perl-modules-5.26 pinentry-curses pollinate popularity-contest postgresql-10 postgresql-client-10 powermgmt-base python3-asn1crypto python3-automat python3-blinker python3-certifi python3-colorama python3-commandnotfound python3-configobj python3-constantly python3-hyperlink python3-idna python3-incremental python3-jinja2 python3-json-pointer python3-jsonpatch python3-pyasn1 python3-pyasn1-modules python3-requests-unixsocket python3-serial python3-service-identity python3.6 python3.6-minimal run-one screen sensible-utils shared-mime-info ssh-import-id ssl-cert sysvinit-utils tcpdump time ubuntu-keyring xauth xfsprogs xkb-data zerofree
2019-04-19 23:32:16,441 DEBUG Obsolete: libbind9-160 libdns-export1102 libdns1102 libgdbm5 libicu60 libirs160 libisc-export169 libisc169 libisccc160 libisccfg160 liblwres160 libntfs-3g88 libperl5.26 libpython3.6 libpython3.6-minimal libpython3.6-stdlib libreadline7 libssl1.0.0 perl-modules-5.26 postgresql-10 postgresql-client-10 python3.6 python3.6-minimal
2019-04-19 23:32:20,143 DEBUG remove_candidates: '{'libpython3.6', 'libpolkit-backend-1-0', 'libirs160', 'libperl5.26', 'libisc169', 'libisccc160', 'python3.6', 'gcc-8-base', 'libicu60', 'libisccfg160', 'libdns-export1102', 'python3.6-minimal', 'libntfs-3g88', 'libpython3.6-minimal', 'python3-pam', 'acpid', 'libdns1102', 'libgdbm5', 'libpolkit-agent-1-0', 'perl-modules-5.26', 'postgresql-10', 'postgresql-client-10', 'libpython3.6-stdlib', 'liblwres160', 'policykit-1', 'libbind9-160', 'libfreetype6', 'libreadline7', 'libssl1.0.0', 'libisc-export169'}'
2019-04-19 23:32:20,834 DEBUG blacklist expr '^postgresql-.*[0-9][0-9].*' matches 'postgresql-10'
2019-04-19 23:32:20,834 DEBUG package 'libicu60' produces an unwanted removal 'postgresql-10', skipping
2019-04-19 23:32:21,803 DEBUG blacklist expr '^postgresql-.*[0-9][0-9].*' matches 'postgresql-10'
2019-04-19 23:32:21,803 DEBUG skipping 'postgresql-10' (in removalBlacklist)
2019-04-19 23:32:21,803 DEBUG 'postgresql-10' scheduled for remove but not safe to remove, skipping
---
root@cosmic:~# du -sh /var/lib/postgresql/*
264M /var/lib/postgresql/10