ci: allow to manually select the Fedora version for Tier 1

Versions that has branched out from Rawhide but are still not released
still have many changes that breaks the CI.

As we want the CI to be more stable for Tier 1, which runs for every MR,
do not make the switch as soon as Rawhide has branched, but when we choose so.

.gitlab-ci.yml

@@ -60,11 +60,11 @@ variables:
   #
   # This is done by running `ci-fairy generate-template` and possibly bumping
   # ".default_tag".
-  ALPINE_TAG:  'tag-4b249f1fd7fc'
+  ALPINE_TAG:  'tag-0959c37ef19b'
-  CENTOS_TAG:  'tag-58487201dcba'
+  CENTOS_TAG:  'tag-70ac400f2325'
-  DEBIAN_TAG:  'tag-288e1002f3ac'
+  DEBIAN_TAG:  'tag-c03f6a5793ce'
-  FEDORA_TAG:  'tag-58487201dcba'
+  FEDORA_TAG:  'tag-70ac400f2325'
-  UBUNTU_TAG:  'tag-288e1002f3ac'
+  UBUNTU_TAG:  'tag-c03f6a5793ce'
 
   ALPINE_EXEC: 'bash .gitlab-ci/alpine-install.sh'
   CENTOS_EXEC: 'bash .gitlab-ci/fedora-install.sh'

.gitlab-ci/config.yml

@@ -72,4 +72,4 @@ distributions:
       - '3.20'
       - '3.19'
       - '3.18'
-      - '3.17'
+      - '3.17'

.gitlab-ci/distros-info.yml

@@ -9,8 +9,9 @@ fedora:
   support: yes
   nm: main
 - version: 41
-  support: yes
+  support: 2025-11-19
   nm: 1.50
+  tier1-default: yes
 - version: 40
   support: 2025-05-13
   nm: 1.46

.gitlab-ci/distros_support.py

@@ -124,7 +124,20 @@ for distro, versions in distros_info.items():
 
 # Select a Tier1 distro
 tier1_distro, tier1_version = "", ""
+
+for fed_ver_info in distros_info["fedora"]:
+    # We prefer the Fedora version marked as tier1-default
+    if fed_ver_info.get("tier1-default", False):
+        for tier in (tier2, tier3):
+            if fed_ver_info["version"] in tier.get("fedora", []):
+                tier1_distro = "fedora"
+                tier1_version = fed_ver_info["version"]
+                tier["fedora"].remove(fed_ver_info["version"])
+
 for distro in ci_distros:
+    if tier1_distro:
+        break
+
     for tier in (tier2, tier3):
         if distro in tier:
             # Exception: we want to use fedora:latest instead of fedora:rawhide because
@@ -142,8 +155,6 @@ for distro in ci_distros:
             if not tier[distro]:
                 del tier[distro]
             break
-    if tier1_distro:
-        break
 
 if not tier1_distro or not tier1_version:
     print("Warn: no suitable distro for Tier 1 found", file=sys.stderr)