pip install old version

[strelnikov]

please upgrade pip with latest version..
currently there is version with from core import ... in init.py

[JunyongYao]

You can try

pip install git+https://github.com/locustio/locust.git  

as a workaround.

[heyman]

A new pre-prelease version was released last week. You need to specify the version explicitly (since it's marked as alpha):

pip install locustio==0.8a2