Using "RequestInformation.HttpStatusCode seems to work for me
try
{
TableOperation operation = TableOperation.Merge(ent);
retval = await table.ExecuteAsync(operation);
}
catch (StorageException sex)
{
if (sex.RequestInformation.HttpStatusCode == (int)HttpStatusCode.PreconditionFailed)
{
TableOperation retrieveOperation = TableOperation.Retrieve<BotSetting>(ent.PartitionKey, ent.RowKey);
TableResult retrievedResult = await table.ExecuteAsync(retrieveOperation);
if (retrievedResult.Result != null)
{
BotSetting bs = retrievedResult.Result as BotSetting;
retval = await TryMerge(table, bs, tries--);
}
}
}