Minor fix

stashr/server.py

@@ -96,7 +96,8 @@ class Server:
 
     def restart_server(self, ignored_signum, ignored_frame):
         app.logger.debug('Restarting Server')
-        self.wsgiserver.stop()
+        if self.wsgiserver is not None :
+            self.wsgiserver.stop()
         try:
             subprocess.check_call([sys.executable, 'start.py'])
         except subprocess.CalledProcessError as e: