Clean install of 15.2 from net-install media followed by zypper --releasever
15.3 dup.

We seem to create an enabled openSUSE-Leap-15.2-1 repo with top-level prio that
contains hardcoded 15.2 instead of $releasever.


lkocman@localhost:/etc/zypp> cat /etc/zypp/repos.d/openSUSE-Leap-15.2-1.repo 
[openSUSE-Leap-15.2-1]
name=openSUSE-Leap-15.2-1
enabled=0
autorefresh=1
baseurl=http://download.opensuse.org/distribution/leap/15.2/repo/oss/
path=/
type=rpm-md
keeppackages=0

lkocman@localhost:/etc/zypp> rpm -qf
/etc/zypp/repos.d/openSUSE-Leap-15.2-1.repo
file /etc/zypp/repos.d/openSUSE-Leap-15.2-1.repo is not owned by any

Unless you disable the repo manually, the upgrade will not update
openSUSE-release packages as zypper dup will insist on using the 15.2
openSUSE-release package. 

lkocman@localhost:~> rpm -qa | grep release
openSUSE-release-ftp-15.2-lp152.575.1.x86_64
openSUSE-release-15.2-lp152.575.1.x86_64
release-notes-openSUSE-15.3.20210129-lp153.1.91.noarch
lkocman@localhost:~> sudo zypper --releasever 15.3 dup
[sudo] password for root: 
Warning: Enforced setting: $releasever=15.3
Loading repository data...
Reading installed packages...
Warning: You are about to do a distribution upgrade with all enabled
repositories. Make sure these repositories are compatible before you continue.
See 'man zypper' for more information about this command.
Computing distribution upgrade...
Nothing to do.



Disabling it fixed the behavior of zypper dup to actually install the 15.3
openSUSE- release package.

lkocman@localhost:/etc/zypp> sudo vim repos.d/openSUSE-Leap-15.2-1.repo 
lkocman@localhost:/etc/zypp> sudo zypper --releasever 15.3 dup
Warning: Enforced setting: $releasever=15.3
Loading repository data...
Reading installed packages...
Warning: You are about to do a distribution upgrade with all enabled
repositories. Make sure these repositories are compatible before you continue.
See 'man zypper' for more information about this command.
Computing distribution upgrade...

The following 2 NEW packages are going to be installed:
  kernel-default-extra kernel-default-optional

The following NEW product is going to be installed:
  "openSUSE Leap 15.3"

The following 2 packages are going to be REMOVED:
  patterns-base-apparmor_opt patterns-base-enhanced_base_opt

The following 2 patterns are going to be REMOVED:
  apparmor_opt enhanced_base_opt

The following product is going to be REMOVED:
  "openSUSE Leap 15.2"

The following 2 packages are going to be upgraded:
  openSUSE-release openSUSE-release-ftp

The following 19 packages are going to be downgraded:
  adobe-sourcesanspro-fonts ifplugd joe libnss_usrfiles2 libzck1
lifecycle-data-openSUSE metamail mpt-status nano
  nano-lang openssh-askpass parallel-printer-support poppler-data rng-tools
site-config tnftp urlscan urlview
  yast2-alternatives

2 packages to upgrade, 19 to downgrade, 2 new, 2 to remove.
Overall download size: 36.0 MiB. Already cached: 0 B. After the operation,
additional 19.6 MiB will be used.
Continue? [y/n/v/...? shows all options] (y): y