Cleanup knownnodes only if network is enabled

src/class_singleCleaner.py

@@ -108,6 +108,7 @@ class singleCleaner(StoppableThread):
             try:
                 # Cleanup knownnodes and handle possible severe exception
                 # while writing it to disk
+                if state.enableNetwork:
                     knownnodes.cleanupKnownNodes()
             except Exception as err:
                 if "Errno 28" in str(err):