* develop-olympus:
[ticket/10205] Reduce nesting in mysql drivers.
[ticket/10205] Rewrite _sql_error implementations to have a single return.
[ticket/10205] Cosmetic changes.
[ticket/10205] Add some columns to the empty fixture file for mssqlnative.
[ticket/10205] Delete stray return.
[ticket/10205] Test failed connection attempts.
[ticket/10205] Check for function existence in mssql connect method.
[ticket/10205] Convert mssqlnative driver to the same logic.
[ticket/10205] Fix a parse error in oracle driver.
[ticket/10205] Fix remaining db drivers.
[ticket/10205] Avoid calling mysqli functions when mysqli is missing.
[ticket/10205] Account for potentially missing extensions in dbal.
Conflicts:
tests/fixtures/empty.xml
b7b8fefdd0