@AmineChikhaoui, thanks for your PR! By analyzing the history of the files in this pull request, we identified @FRidh to be a potential reviewer.

Nixpkgs is a curated set where we try to maintain only a single version of each package in order to prevent collisions between multiple versions in a closure. flask_assets is a relatively minor package (though a dependency of octoprint) so that doesn't warrant an extra version.

If flask_assets cannot handle the current version of flask, then they need to release a version that can. Until then, that could mean this package in Nixpkgs is broken.

If the purpose was to fix octoprint, then within that closure the older flask could be used. Are you sure the older flask is absolutely needed? Is there an issue upstream?

@FRidh the changed pkg is locustio. there is no changes to neither flask_assets/octoprint

@AmineChikhaoui sorry, I misread the diff. Even so, its the same. We won't include an extra version of a package. What does upstream say regarding compatibility with 0.12?

@FRidh so I think you're right it's probably better to fix it upstream as I tried git checkout v0.7.2; make test and reproduced the issue with Flask-0.12. I'll file an issue then.
But meanwhile should the pkg stay broken on 17.03 ?

@AmineChikhaoui it must have been broken already on the release of 17.03 then, since we have flask 0.12 since then.

opened locustio/locust#637

Thanks!