Don't raise if there is no matching entry

slapos/networkcachehelper.py

@@ -198,6 +198,7 @@ def helper_download_network_cached(dir_url, cache_url,
         matching_entry_list.append(tags)
       except Exception:
         pass
+    if matching_entry_list:
     # If a strategy is defined, call it to determine best entry
       if strategy:
         best_entry = strategy(matching_entry_list)
@@ -210,8 +211,6 @@ def helper_download_network_cached(dir_url, cache_url,
 
       # download best entry
       file_descriptor = nc.download(best_entry.get('sha512'))
-
-    if file_descriptor is not None:
       return file_descriptor, tags
     else:
       logger.info('No matching entry to download from network cache: %s'\