efcore: EFCore Delete And Add will merge to Update，and throw concurrency Exception

i`m trying to update my code from ef6 to efcore . and get a concurrency exception

i have a Demo Entity

 public class itemMap : IEntityTypeConfiguration<item>
    {
        public void Configure(EntityTypeBuilder<item> builder)
        {
            builder.HasKey(t => t.ItemGID);
            builder.Property(t => t.ItemGID)
                .IsRequired()
                .HasMaxLength(100);
            builder.Property(t => t.ItemID)
                .IsRequired()
                .HasMaxLength(100);
            builder.ToTable("item");
            builder.Property(t => t.ItemGID).HasColumnName("ItemGID");
            builder.Property(t => t.ItemID).HasColumnName("ItemID");
            builder.Property(t => t.TS)
                    .ValueGeneratedOnUpdate().IsConcurrencyToken();
        }
    }

DemoCode:

            using (var context = new demoContext())
            {
                var defaultPrimaryKey = "test";
                var data = context.Set<item>().Find(defaultPrimaryKey);
                context.Set<item>().Remove(data);
                var item1 = new item
                {
                    ItemGID = defaultPrimaryKey,ItemID = defaultPrimaryKey,
                    TS = DateTime.Now
                };
                context.Set<item>().Add(item1);
                context.SaveChanges();
            }

this scene is when you call Set<T>.Remove and then call Set<T>.Add , and the entity primary key is same . 1. EFCore SaveChange will transfer to one update sql. 2. EF6 SaveChange will transfer to two sql，one is delete sql and another is insert sql. will , this is smart for EFCore ,but with ConcurrencyToken property , the problem is the update sql where condition TS is ‘NewValue’ not DatabaseValue , so get a concurrency exception. i think if efcore merge delete and insert to update , the ConcurrencyToken property value will use databaseValue , not the insert new value ? i had tested on sqlserver , and even get this error , so it is not problem for provider .

Exception message:
Microsoft.EntityFrameworkCore.DbUpdateConcurrencyException:“Database operation expected to affect 1 row(s) but actually affected 0 row(s). Data may have been modified or deleted since entities were loaded. See http://go.microsoft.com/fwlink/?LinkId=527962 for information on understanding and handling optimistic concurrency exceptions.”

LogSql is :   Executed DbCommand (2ms) [Parameters=[@p3='test' (Nullable = false) (Size = 100), @p0='' (Size = 100), @p4='test' (Nullable = false) (Size = 100), @p1='' (Size = 100), @p2='2019-06-29T14:59:15' (DbType = DateTime), @p5='2019-06-29T14:59:15' (DbType = DateTime)], CommandType='Text', CommandTimeout='30']
UPDATE `item` SET `ItemDesc` = @p0, `ItemName` = @p1, `TS` = @p2
WHERE `ItemGID` = @p3 AND `ItemID` = @p4 AND `TS` = @p5;
SELECT ROW_COUNT();

@p5 is insert new value , so affected 0 row(s). if @p5 is databaseValue they will be ok.

Further technical details

EF Core version: Microsoft.EntityFrameworkCore 2.2.4 Database Provider: Pomelo.EntityFrameworkCore.MySql 2.2 Operating system: Windows 10 IDE: (e.g. Visual Studio 2019 16.1.3)