Today I found an issue related to another issue in the google-api-python-client:
googleapis/google-api-python-client#2485

To summarize, when both api-client and google-api-python-client are installed, the latter one overwrites the __init__.py file of the api-client. In that case, none of the imports from apiclient directly work.

One possible way would be to change all the imports to the ones from nested modules, e.g.:

from apiclient.client import APIClient

instead of:

from apiclient import APIClient

I know, this is not ideal, but I can't come up with a better solution for those cases, when both packages are required. Maybe google-api-python-client will solve this issue in the near future.