deal with broken links post-upload

[Ambrosiani]

implement https://github.com/lokal-profil/LSH/blob/4f4213c87847782e8004802bd928c419fe005440/py_postUpload.py#L24

[Ambrosiani]

broken links in current upload: https://petscan.wmflabs.org/?language=commons&project=wikimedia&categories=Files%20with%20broken%20file%20links%0D%0AImages%20from%20Nordiska%20museet%3A%202018-12&ns%5B6%5D=1&search_max_results=500&interface_language=en&&doit=