Open Radar

 
Summary:
1. en_US and en-US are mixed: current and autoupdatingCurrent uses en_US for localeIdentifier but en-US for collatorIdentifier, inconsistent format. 
2. us1 == autoupdatingCurrent, autoupdatingCurrent == current, but current != us1, transitivity of equality is broken.
3. current and autoupdatingCurrent uses en-US for collatorIdentifier in app but en_US in playground, inconsistent.
4. displayName(forKey:value:) does not work for current and autoupdatingCurrent in playground, always returning nil.

Steps to Reproduce:
1. Run sample app and read console logs.
2. Run sample playground and read console logs.

Code:

        let us1 = Locale(localeIdentifier: "en_US")
        let us2 = Locale(localeIdentifier: "en-US")
        let current = Locale.current
        let autoupdatingCurrent = Locale.autoupdatingCurrent
        
        print("localeIdentifier:", us1.localeIdentifier, us2.localeIdentifier, current.localeIdentifier, autoupdatingCurrent.localeIdentifier)
        print("collatorIdentifier:", us1.collatorIdentifier, us2.collatorIdentifier, current.collatorIdentifier, autoupdatingCurrent.collatorIdentifier)
        
        print("us1 == us2", us1 == us2)
        print("us1 == current", us1 == current)
        print("us1 == autoupdatingCurrent", us1 == autoupdatingCurrent)
        print("us2 == current", us2 == current)
        print("us2 == autoupdatingCurrent", us2 == autoupdatingCurrent)
        print("current == autoupdatingCurrent", current == autoupdatingCurrent)
        
        print("us1 localized localeIdentifier:", us1.displayName(forKey: .identifier, value: us1.localeIdentifier))
        print("us2 localized localeIdentifier:", us2.displayName(forKey: .identifier, value: us2.localeIdentifier))
        print("current localized localeIdentifier:", current.displayName(forKey: .identifier, value: current.localeIdentifier))
        print("autoupdatingCurrent localized localeIdentifier:", autoupdatingCurrent.displayName(forKey: .identifier, value: autoupdatingCurrent.localeIdentifier))