require virtualenv to be ready before installing packages with pip

This should fix the first part of issue #430 "pip3 missing in the virtualenv ?"

using a proxy for download is not addressed here

manifests/pip.pp

@@ -73,6 +73,11 @@
   $python_provider = getparam(Class['python'], 'provider')
   $python_version  = getparam(Class['python'], 'version')
 
+  if $virtualenv != 'system' {
+    Python::Pyvenv <| |> -> Python::Pip[$name]
+    Python::Virtualenv <| |> -> Python::Pip[$name]
+  }
+
   # Get SCL exec prefix
   # NB: this will not work if you are running puppet from scl enabled shell
   $exec_prefix = $python_provider ? {

manifests/pyvenv.pp

@@ -47,8 +47,6 @@
       case $facts['os']['distro']['codename'] {
          'xenial','bionic','cosmic','disco',
         'jessie','stretch','buster': {
-          notify {"python3_venv_package: $python3_venv_package":
-          }
           package {$python3_venv_package:
             before => File[$venv_dir],
           }