Extra Informations:
   
- I've installed flint on my ubuntu 18.04 workstation and I got same error.

- I found out that it fail because the user it try to create already exist in the repository.
    + I think it should handle this situation somehow, it is probably very common that an uploaded repository already contain the "Flint Account" username.

- I tried again on Chiselapp with a repo which doesn't contain a user that match my chiselapp account.
    + But it still does the same error. (as the opposite as on my own flint setup)