build fix, fix error introduced with 091b246bb0111357edbb9703ea342a944b04deb6

Fixes the following issue:

  1) Failure:
ActiveRecord::MySQLPurgeTest#test_establishes_connection_to_test_database [test/cases/tasks/mysql_rake_test.rb:200]:
not all expectations were satisfied
unsatisfied expectations:
- expected exactly once, not yet invoked: ActiveRecord::Base.establish_connection(:test)
satisfied expectations:
- allowed any number of times, invoked once: #<Mock:0x2349430>.recreate_database(any_parameters)
- allowed any number of times, invoked once: ActiveRecord::Base.establish_connection(any_parameters)
- allowed any number of times, invoked once: ActiveRecord::Base.connection(any_parameters)
tests, run adapter specific rake tests only for the right adapter.