cleanup warnings
cleanup warnings

- fix partition selection function
- get ruby >= 2 calling the correct no-gvl function

zendesk/Hermann,zendesk/Hermann,rtyler/Hermann,lookout/hermann,rtyler/Hermann,braintree/hermann,reiseburo/hermann,reiseburo/hermann,braintree/hermann,lookout/hermann,lookout/hermann,reiseburo/hermann,rtyler/Hermann,zendesk/Hermann,braintree/hermann