I found this bug while working with a DataTable. I added a primary key column to a DataTable, than added one row to that table, removed that row, and added row with the same key to the table. This works. When I tried to call RejectChanges() on it, I got ConstraintException saying that value is already present. Here is the example:

    var dataTable = new DataTable();
    var column = new DataColumn("ID", typeof(decimal));
    dataTable.Columns.Add(column);
    dataTable.PrimaryKey =  new [] {column };

    decimal id = 1;

    var oldRow = dataTable.NewRow();
    oldRow[column] = id;

    dataTable.Rows.Add(oldRow);
    dataTable.AcceptChanges();

    oldRow.Delete();

    var newRow = dataTable.NewRow();
    newRow[column] = id;

    dataTable.Rows.Add(newRow);
    dataTable.RejectChanges(); // This is where it crashes

I think since the row is deleted, exception should not be thrown (constraint is not violated because row is in deleted state). Is there something I can do about this? Any help is appreciated.