world: London (UK) can be added multiple times
When adding a city to world clock, the expected behavior is for that city to be disabled the next time the user tries to add it. For example, if I add Cairo to world clocks, trying to add it a second time, even after closing and reopening the app, shows me this:
But for London (UK), it can be added multiple times if the app is closed and reopened:
steps to reproduce
- open world clock
- click "add location" and add London (UK)
- close clocks using
kill gnome-clocks
- open clocks and navigate to world clock
- repeat the process to add London(UK)
- now you have two Londons, both in UK, in your cities list.