During internal testing of upgrades between RHEL 9.4 and 9.6, we noticed that a freshly installed RHEL 9.6 differed from an 9.4 EUS installation that was subsequently upgraded to 9.6, in several packages.

Upon inspection, we found that pam and cronie/cronie-anacron were not updated during the upgrade, because the versions provided in 9.4 EUS are considered newer than in 9.6:

• pam:
  • "1.5.1-23.el9_4.x86_64" on 9.4 EUS
  • "1.5.1-23.el9.x86_64" on 9.6
• cronie / cronie-anacron:
  • "1.5.7-13.el9_4.x86_64" on 9.4 EUS
  • "1.5.7-13.el9.x86_64"

Further inspection of the changelogs of the two binary RPMs suggested that potentially neither may be a clear subset of the other in terms of patches.

We expected that an upgrade would bring us to the same state as a fresh install, if the list of installed packages is identical, but this doesn't seem to be the case. Is this behaviour expected?