Fix detected_device not being set

src/calibre/devices/usbms/device.py

@@ -39,6 +39,11 @@ class USBDevice:
         self.idVendor = dev[0]
         self.idProduct = dev[1]
         self.bcdDevice = dev[2]
+        if iswindows:
+            # Getting this information requires communicating with the device
+            # we only do that in the can_handle_windows() method, if needed.
+            self.manufacturer = self.serial = self.product = ''
+        else:
             self.manufacturer = dev[3]
             self.product = dev[4]
             self.serial = dev[5]