Do not do update() in discover_single (#542)

kasa/discover.py

@@ -260,6 +260,7 @@ class Discover:
         port: Optional[int] = None,
         timeout=5,
         credentials: Optional[Credentials] = None,
+        update_parent_devices: bool = True,
     ) -> SmartDevice:
         """Discover a single device by the given IP address.
 
@@ -271,8 +272,9 @@ class Discover:
         :param host: Hostname of device to query
         :param port: Optionally set a different port for the device
         :param timeout: Timeout for discovery
-        :param credentials: Optionally provide credentials for
-            devices requiring them
+        :param credentials: Credentials for devices that require authentication
+        :param update_parent_devices: Automatically call device.update() on
+            devices that have children
         :rtype: SmartDevice
         :return: Object for querying/controlling found device.
         """
@@ -330,7 +332,9 @@ class Discover:
         if ip in protocol.discovered_devices:
             dev = protocol.discovered_devices[ip]
             dev.host = host
-            await dev.update()
+            # Call device update on devices that have children
+            if update_parent_devices and dev.has_children:
+                await dev.update()
             return dev
         elif ip in protocol.unsupported_devices:
             raise UnsupportedDeviceException(