Comment 9 for bug 178906

There is no bug, because there is no such thing as PDO::SQlite3
You can use the string sqlite as a DSN for the PDO driver, as in
$dbHandle = new PDO('sqlite:test-sqlite3.db');

which opens a connection to a sqlite3 database.
The PDO sqlite dirver supports both sqlite2 and sqlite3 and is installed by the package php-sqlite.
To connect to a sqlite2 database, you would use
$dbHandle = new PDO('sqlite2:test-sqlite2.db');

The package php-sqlite3 installs the PECL SQLite3 extension,which is a completely different animal.
It is used as follows:
$dbHandle = new SQLite3('test.db');