[gnome-boxes/recommended-downloads-always-look-for-latest-version-in-osinfo-db: 4/5] downloader, logos: Fallback to "upgrades" when "derives_from" is empty

[Felipe Borges <felipeborges src gnome org>]

commit 5c3cb694b0bfd6f2882b0fae90da88bc7919c41c
Author: Felipe Borges <felipeborges gnome org>
Date:   Wed Mar 2 11:48:37 2022 +0100

    downloader, logos: Fallback to "upgrades" when "derives_from" is empty
    
    Boxes iterates over the logo list based on the Osinfo "DERIVES_FROM"
    relationship between OS versions.
    
    In case of OSes like RHEL9, which don't derive directly from RHEL8,
    we should use the "UPGRADES" relationship as a fallback. This helps
    us always show an OS logo when available.

 src/downloader.vala | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/downloader.vala b/src/downloader.vala
index d6b22abd..90b03db6 100644
--- a/src/downloader.vala
+++ b/src/downloader.vala
@@ -41,6 +41,9 @@ public static string fetch_os_logo_url (Osinfo.Os os) {
 
         string logo_url = null;
         var derived = os.get_related (Osinfo.ProductRelationship.DERIVES_FROM);
+        if (derived.get_length () == 0)
+            derived = os.get_related (Osinfo.ProductRelationship.UPGRADES);
+
         while (derived.get_length () > 0 && logo_url == null) {
             // FIXME: Does Osinfo allows deriving from multiple OSs?
             var parent = derived.get_nth (0) as Osinfo.Os;