Fix duplicate virtualenv declaration
Fix duplicate virtualenv declaration

Tests on this module are failing with

Error: Cannot reassign variable virtualenv at
/etc/puppet/modules/python/manifests/virtualenv.pp:102

According to puppet, variable reassignment is not allowed:
https://docs.puppetlabs.com/puppet/latest/reference/
lang_variables.html#no-reassignment

Using a new var for the reassingment to avoid that problem

ByteInternet/puppet-python,adevore/puppet-python,ByteInternet/puppet-python,adevore/puppet-python