Update on non-en-US alpha bundles results in empty dialog being shown

If I update a germen 5.5a5 to 5.5a6 I am greeted with the attached image. There is even no button to cancel this dialog which is pretty confusing. Closing it, though, leads to the changelog being shown.

I guess this dialog pops up in the first place because of the do-you-want-to-use-english-for-this-site-question which is supposed to be shown.