It looks like conan is 'broken' in the CI scripts. appveyor.yml appears to be getting the latest 2.0.9 version of conan, which I think changes 'conan user' to 'conan remote login' (or something like that). The appveyor.yml scripts should be updated to work with the new conan 2.0.x versions or downgrade the pip install conan to something like pip install conan==1.60.2 or whatever was the last working version.
