Fix malformed cache data when reusing cache

The delta entry required the branch as first level to store data.

Signed-off-by: Dylan Aïssi <dylan.aissi@collabora.com>

bin/packaging-check-delta

@@ -243,7 +243,7 @@ def compute_delta(data, cache=None):
                                     branch=branch,
                                 )
                             pkg_delta = {branch: delta_cached}
-                            add_delta_entry(package.name, delta_cached)
+                            add_delta_entry(package.name, pkg_delta)
                             continue
                         else:
                             logging.debug(