update-source-catalog: Fix case where a variaton does not point at the base layer (i.e. most builds) (LP: #2033168)

debian/changelog

@@ -1,3 +1,10 @@
+livecd-rootfs (23.10.24) UNRELEASED; urgency=medium
+
+  * update-source-catalog: Fix case where a variaton does not point at the
+    base layer (i.e. most builds) (LP: #2033168) 
+
+ -- Michael Hudson-Doyle <michael.hudson@ubuntu.com>  Mon, 28 Aug 2023 10:39:52 +1200
+
 livecd-rootfs (23.10.23) mantic; urgency=medium
 
   * i386 foreign-arch support was added for the canary image before 23.04

update-source-catalog

@@ -44,7 +44,7 @@ for entry in output:
 else:
     # No entry with this id found, so add a new one.
 
-    if template['variations']:
+    if 'variations' in template:
         for variation in template['variations'].values():
             if variation['path'] == opts.squashfs:
                 variation['size'] = int(opts.size)