SqlServerConnection::transaction() should use PDO transactions with sqlsrv driver (see issue #1882)

[Corvillus]

The connection seems to do transactions properly if the generic PDO transaction implementation is called instead of the raw "begin tran / commit tran / rollback tran" commands get called on the sqlsrv driver.

[taylorotwell]

OK. I know we changed it for a reason. So I'm assuming this change is going to break other people?

[Corvillus]

Yeah, issue #534. Essentially sqlsrv (the native Windows driver) supports PDO transactions. dblib (the Linux FreeTDS driver) does not. So explicitly checking for sqlsrv as the driver name and calling the generic Connection::transaction() (PDO implementation) shouldn't break it for the dblib users that still need the raw transaction commands, but it would probably be good for a *nix user to test first before merging.

[WMeldon]

I can run a test on this if no one else is running the dblib drivers.

[Corvillus]

Sure, that would be great. I keep meaning to test on my Mac, but keep forgetting about this (until the error reappears after a composer update that is). #2143 seems to be a different fix to the same issue but it fails integration tests.

[WMeldon]

Whoops, didn't read this carefully enough. I'm using dblib so I won't be able to test this outside of the initial if statement.

Haven't got any Windows servers to test this on.

[taylorotwell]

Done on 4.0 branch.