SQL Server 2014 reseting isolation level

Question

Hi,
Working with C# application accessing SQL Server 2012 and 2014 using ADO.NET.
There seem to be a change regarding isolation level reset when returning connection to pool.
Previous versions of SQL Server does not reset the isolation level on the connection (unfortunately) as claimed here (http://support.microsoft.com/?id=972915).
However it seems this has changed with SQL Server 2014.
If running the attached code it shows that the isolation level in fact is reset when running against a SQL Server 2014 instance but not 2012.
Can anyone on the SQL Server team confirm that this is an intended change that is here to stay? I have not seen any documentation on this so far in the behavior changes documented here: http://msdn.microsoft.com/en-us/library/ms143359.aspx
class Program
static void Main(string[] args)
TestIsolationLevelReset();
Console.ReadLine();
public static void TestIsolationLevelReset()
var connectionString = @"Data Source=(local); Integrated Security=true; Initial Catalog=master;";
var commandText = @"select cast (transaction_isolation_level as nvarchar) + ' - ' + CAST(@@spid as nvarchar) from sys.dm_exec_sessions where (session_id = @@SPID)";
using (var conn = new SqlConnection(connectionString))
conn.Open();
var cmd = new SqlCommand(commandText, conn);
Console.WriteLine(cmd.ExecuteScalar());
using (var tran = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions() { IsolationLevel = IsolationLevel.Serializable }))
using (var conn = new SqlConnection(connectionString))
conn.Open();
var cmd = new SqlCommand(commandText, conn);
Console.WriteLine(cmd.ExecuteScalar());
tran.Complete();
using (var conn = new SqlConnection(connectionString))
conn.Open();
var cmd = new SqlCommand(commandText, conn);
Console.WriteLine(cmd.ExecuteScalar());

Answer 1

Is that possible to know, or must I always ask SQL Server what has been negotiated?
The negotiated version is the highest version supported by both client and server.  According to
http://msdn.microsoft.com/en-us/library/dd304523.aspx, the Server versions are:
SQL Server 7.0 7.0
SQL Server 2000 7.1
SQL Server 2000 SP1 7.1 Revision 1
SQL Server 2005 7.2
SQL Server 2008 7.3.A
SQL Server 2008 R2 7.3.B
SQL Server 2012 7.4
SQL Server 2014 7.4
I can't speak to the exact TDS versions supported by SqlClient.  On my PC, .NET 4.0 and above against a SQL 2014 box used TDS 7.4 where as 3.5 and earlier used TDS 7.3. 
Based on this, I wouldn't expect the isolation level behavior change if SQL Server 2012 and 2014 is the only difference.  What version of .NET are you using?
Dan Guzman, SQL Server MVP, http://www.dbdelta.com