TransactionScope.cs

public static TransactionScope New(TransactionScopeOption transactionScopeOption = TransactionScopeOption.Required, IsolationLevel isolationLevel = IsolationLevel.ReadCommitted, TimeSpan? timeout = null)
{
	// NOTE: this is a fix, to avoid inner transaction timeout's to shorten the outer one...
	if (Transaction.Current != null && transactionScopeOption == TransactionScopeOption.Required)
		timeout = TimeSpan.FromMinutes(15);

	var options = new TransactionOptions
	{
		IsolationLevel = isolationLevel,
		Timeout = timeout ?? TransactionManager.DefaultTimeout
	};

	return new TransactionScope(transactionScopeOption, options);
}