Selenium WebDriver 2.5.0, 2.6.0 fails when selecting options from select boxes

We are consistently having trouble with selenium-webdriver > 2.5.0 where whenever we try to select an option from a <select> Capybara complains:

No such option 'Foo' in this select box. Available options: 'Foo', 'Bar', 'Baz' (Capybara::OptionNotFound)

This seems to happen with both old and new versions of Firefox. Our workaround so far is to freeze the gem at version 0.2.2.