Fix user for v7 migration

src/Umbraco.Core/Models/Membership/User.cs

@@ -54,7 +54,6 @@ namespace Umbraco.Core.Models.Membership
             _isLockedOut = false;
             _startContentIds = new int[] { };
             _startMediaIds = new int[] { };
-
         }
 
         /// <summary>

src/Umbraco.Core/Persistence/Factories/UserFactory.cs

@@ -36,6 +36,13 @@ namespace Umbraco.Core.Persistence.Factories
                 user.InvitedDate = dto.InvitedDate;
                 user.TourData = dto.TourData;
 
+                // we should never get user with ID zero from database, except
+                // when upgrading from v7 - mark that user so that we do not
+                // save it back to database (as that would create a *new* user)
+                // see also: UserRepository.PersistNewItem
+                if (dto.Id == 0)
+                    user.AdditionalData["IS_V7_ZERO"] = true;
+
                 // reset dirty initial properties (U4-1946)
                 user.ResetDirtyProperties(false);
 

src/Umbraco.Core/Persistence/Repositories/Implement/UserRepository.cs

@@ -434,6 +434,17 @@ ORDER BY colName";
 
         protected override void PersistNewItem(IUser entity)
         {
+            // the use may have no identity, ie ID is zero, and be v7 super
+            // user - then it has been marked - and we must not persist it
+            // as new, as we do not want to create a new user - instead, persist
+            // it as updated
+            // see also: UserFactory.BuildEntity
+            if (((User) entity).AdditionalData.ContainsKey("IS_V7_ZERO"))
+            {
+                PersistUpdatedItem(entity);
+                return;
+            }
+
             ((User) entity).AddingEntity();
 
             // ensure security stamp if missing