Pin RHEL 9 to 9.1

[cottsay]

RHEL 9.2 has been released and there are packages in EPEL which must be rebuilt before we can begin using it. This change makes it possible to specify minor RHEL version numbers in the EL_RELEASE parameter and changes the default to 9.1.

To do this, all existing uses of EL_RELEASE were converted to use only the major version number using bash parameter substitution, and a string replace operation changes the use of $releasever in the yum/dnf repository configurations to specifically use the major-minor instead of just the major.

Note than EPEL nor our own repositories support major-minor RHEL versions and must use only the major version number, which is why I'm modifying the configs directly rather than simply changing $releasever altogether.

Canary build:

[nuclearsandwich]

Note than EPEL nor our own repositories support major-minor RHEL versions and must use only the major version number, which is why I'm modifying the configs directly rather than simply changing $releasever altogether.

In your opinion, long term, is this something that should change for both or either the ROS repos or EPEL?

[cottsay]

In your opinion, long term, is this something that should change for both or either the ROS repos or EPEL?

I don't think so. If we did, it would be a superficial redirect. RHEL actually does release updates to some minor releases, so it makes sense for them, but EPEL is always best-effort-latest, which is effectively what we're doing too.

[cottsay]

This change has been deployed.

[ros-discourse]

This pull request has been mentioned on ROS Discourse. There might be relevant details there:

https://discourse.ros.org/t/ros-infrastructure-updates-from-may-2023https-discourse-ros-org-t-infrastructure-community-meeting-2023-05-17-31268-6/31759/1