Metaflow/community

Hi Metaflow,
I'm having issues with the @conda and @conda_base functionality. It doesn't seem to work at all on my machine. I've tried it with different versions of numpy and pandas and different versions of python interpreter. I've also reinstalled my anaconda3 from scratch but it didn't help. The version of a library has some correlation with the version of python interpreter but no correlation with what I specify in the decorator.
My code is

from metaflow import FlowSpec, step, conda


class CondaFlow(FlowSpec):

    @conda(libraries={'numpy':'1.15.4'})
    @step
    def start(self):
        import numpy as np
        print('numpy', np.__version__)

        self.next(self.end)

    @step
    def end(self):
        pass

if __name__ == '__main__':
    CondaFlow()

I run it as follows

python conda_flow.py --environment=conda run

which outputs

Metaflow 2.0.3 executing CondaFlow for user:ayorgo
Validating your flow...
    The graph looks good!
Running pylint...
    Pylint not found, so extra checks are disabled.
2020-04-09 11:09:17.711 Bootstrapping conda environment...(this could take a few minutes)
2020-04-09 11:09:42.926 Workflow starting (run-id 39):
2020-04-09 11:09:43.940 [39/start/127 (pid 18442)] Task is starting.
2020-04-09 11:09:44.334 [39/start/127 (pid 18442)] numpy 1.16.2
2020-04-09 11:09:44.416 [39/start/127 (pid 18442)] Task finished successfully.
2020-04-09 11:09:45.438 [39/end/128 (pid 18462)] Task is starting.
2020-04-09 11:09:45.786 [39/end/128 (pid 18462)] Task finished successfully.
2020-04-09 11:09:45.787 Done!

What am I doing wrong?
Thank you