Bootstrap 3.3.5, iOS 8.4.1 modal scrolls background when selecting input field

Created by: ghost

When i select a Form Field (Select and/or Textbox) In a Modal, the page in the Background scolls to top. This also happens on the Bootstap example page: http://getbootstrap.com/javascript/#modals-related-target

Works fine in Chrome, IE and Safari on Windows, and also in Safari on a Macbook. The only troublemaker ist the iPhone and iPad Mini with IOS version 8.4.1.

All CSS hacks with modal-open didnt fix the problem.