Call detectDatabasePlatform only once

[rosier]

Database platform detection is triggered twice if Doctrine/DBAL/Connection::getDatabasePlatform() is called before Doctrine/DBAL/Connection::connect()

[doctrinebot]

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thank you for creating this pull request. I have automatically opened an issue
on our Jira Bug Tracker for you. See the issue link:

http://www.doctrine-project.org/jira/browse/DBAL-1127

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[Ocramius]

@rosier requires a test case

[deeky666]

Why is this change necessary? Connection::ping() calls Connection::connect() as the beginning, so it ensures the platform is set.

[rosier]

The platform isn't set anymore in connect() with this PR.

In the current version of Connection the following calls are triggered:
getDatabasePlatform() => detectDatabasePlatform() => getDatabasePlatformVersion() => connect() at this point because the platform isn't set yet connect() calls detectDatabasePlatform() again.

This PR removes the call to detectDatabasePlatform() from connect() to stop that from happening.

[rosier]

@Ocramius Connection::detectDatabasePlatform() is a private function. I'm not sure if there is a good way to test that it is called only once.

[Ocramius]

@rosier try looking at the wrapped driver: that one can be mocked

[deeky666]

Merged manually via de75561. Verified the issue by adding a test. Thanks @rosier !