https://github.com/plathrop/puppet-module-supervisor/blob/master/manifests/init.pp#L198
I am not sure about this, but for me this dependency caused nothing but problems on debian 8.
May be I'm doing something wrong.
I have pip already installed, but I was forced to add python-pip package to my manifest. And puppet 4.4 could not install it:(. So I just commented out this requirement, and everything worked.