twitter/bootstrap — pull request #1092 by dwightwatson (2012-01-21 13:55:59+00:00)
Title: Fixed issue with extra padding being applied with errors on forms with the class .form-stacked.

Forms with the class .form-stacked would add padding above and below form elements when they had the class .error. This spreads the elements out of the page and can be confusing (especially when the error class is being added/removed through JavaScript and moving things up and down).