Travis is dying with 'The command "pip install -r requirements.txt --use-mirrors" failed' because apparently:
--use-mirrors has been deprecated and will be removed in the future. Explicit uses of --index-url and/or --extra-index-url is suggested.
I think we can probably just drop the use mirrors argument, I don't think we actually need it. (If anyone has time to commit an edit to the .travis.yml and check)
Travis is dying with 'The command "pip install -r requirements.txt --use-mirrors" failed' because apparently: --use-mirrors has been deprecated and will be removed in the future. Explicit uses of --index-url and/or --extra-index-url is suggested.