Fixes: U4-6998 User language drop down is incorrect when default language is used

src/Umbraco.Core/Services/LocalizedTextService.cs

@@ -191,6 +191,23 @@ namespace Umbraco.Core.Services
             return attempt ? attempt.Result : currentCulture;
         }
 
+        /// <summary>
+        /// HAAAAAAAAAAACK! Used for backwards compat to convert a user's real culture code to a region code - normally this would be two letters
+        /// </summary>
+        /// <param name="currentCulture"></param>
+        /// <returns></returns>
+        public string ConvertToRegionCodeFromSupportedCulture(CultureInfo currentCulture)
+        {
+            if (currentCulture == null) throw new ArgumentNullException("currentCulture");
+
+            if (_fileSources == null) return currentCulture.Name;
+            
+            var attempt = _fileSources.Value.TryConvert4LetterCultureTo2Letter(currentCulture);
+            return attempt 
+                ? attempt.Result 
+                : currentCulture.Name;
+        }
+
         private string GetFromDictionarySource(CultureInfo culture, string area, string key, IDictionary<string, string> tokens)
         {
             if (_dictionarySource.ContainsKey(culture) == false)