When I change content of exclude list in proxy configuration, save button doesn't become active, as result content remains unchanged

Steps to reproduce:

1. Enable and configure proxy
2. Add records to exclude list
3. Update content

Expected result:
Save button becomes active, changes are saved on prossing it

Actual:
Save button remains disabled, changes can't be saved

Workaround:
Do a change in hostname/port, in this case changes in exclude list are taken into account