[6.x] Fix handleBeginTransactionException method calling pdo property instead of getPdo() method

[kanidjar]

Fix handleBeginTransactionException method calling pdo property instead of getPdo() method (#31230)

Description:

When connection to database is lost and transaction is retried, an exception is thrown.

[2020-01-24 15:00:16] production.ERROR: Symfony\Component\Debug\Exception\FatalThrowableError: Call to undefined method Closure::beginTransaction() in /var/www/html/vendor/illuminate/database/Concerns/ManagesTransactions.php:157
Stack trace:
#0 /var/www/html/vendor/illuminate/database/Concerns/ManagesTransactions.php(125): Illuminate\Database\Connection->handleBeginTransactionException(Object(PDOException))
#1 /var/www/html/vendor/illuminate/database/Concerns/ManagesTransactions.php(105): Illuminate\Database\Connection->createTransaction()
#2 /var/www/html/vendor/illuminate/database/Concerns/ManagesTransactions.php(23): Illuminate\Database\Connection->beginTransaction()
#3 /var/www/html/vendor/illuminate/database/DatabaseManager.php(349): Illuminate\Database\Connection->transaction(Object(Closure))
#4 /var/www/html/vendor/illuminate/support/Facades/Facade.php(261): Illuminate\Database\DatabaseManager->__call('transaction', Array)
#5 /var/www/html/app/Services/PriceService.php(55): Illuminate\Support\Facades\Facade::__callStatic('transaction', Array)

The exception is thrown because of line 157 calling $this->pdo instead of $this->getPdo()

Same bug was detected in Laravel 5.3 but was not linked to the same file.

#15927

Steps To Reproduce:

Lose connection to database during transaction creation (hard to reproduce but easy to fix)

[GrahamCampbell]

Please revert the other changes to the file.

[kanidjar]

@GrahamCampbell Done

[L3o-pold]

@GrahamCampbell can we merge this into the next release?

[GrahamCampbell]

If this is merged before early afternoon (UK time) tomorrow, then it will likely be included in tomorrow's release.

[GrahamCampbell]

It is much more likely to be merged if you add tests that cover this code, that fail before this PR, and pass afterwards.

[driesvints]

Other calls to the pdo property are also covered with getPdo so this seems okay 👍