Flickr (or YahooID) decided, that it would not grant access to my account any more - apparently not knowing the location I'm connecting from is a reason to deny access. I could have reclaimed the account, if only I had not entered a faux phone number on registration (a picture hoster does not need my phone number, thankyouverymuch). Thankfully, my old laptop still had an active flickr login, so that I could at least all my data on there and I will self-host from now on.
For now it's just some duct tape programming, since I'm also planning to get rid of the dependency hell that is the Ruby-Jekyll world.
So thanks flickr, I guess, for another reminder that you should not unnecessarily depend on third parties.