Cleanup knownnodes only if network is enabled

Author: g1itch

src/class_singleCleaner.py

@@ -108,7 +108,8 @@ def run(self):  # pylint: disable=too-many-branches
             try:
                 # Cleanup knownnodes and handle possible severe exception
                 # while writing it to disk
-                knownnodes.cleanupKnownNodes()
+                if state.enableNetwork:
+                    knownnodes.cleanupKnownNodes()
             except Exception as err:
                 if "Errno 28" in str(err):
                     self.logger.fatal(