Merge pull request #2177 from umbraco/temp-U4-10384

U4-10384 Error when changing content type on media item

src/Umbraco.Core/Models/PropertyCollection.cs

@@ -93,6 +93,10 @@ namespace Umbraco.Core.Models
                         //NOTE: Consider checking type before value is set: item.PropertyType.DataTypeId == property.PropertyType.DataTypeId
                         //Transfer the existing value to the new property
                         var property = this[key];
+                        if (item.Id == 0 && property.Id != 0)
+                        {
+                            item.Id = property.Id;
+                        }
                         if (item.Value == null && property.Value != null)
                         {
                             item.Value = property.Value;