Load virtualenv with pyenv and not pyenv-virtualenv.

Currently if one have pyenv but not pyenv-virtualenv the
virtualenvwrapper is never loaded. If no pyenv-virtualenvwrapper is
present, then try to load the default python virtualenvwrapper tool.

Fix sorin-ionescu#1413

modules/python/init.zsh

@@ -92,14 +92,19 @@ if (( $+VIRTUALENVWRAPPER_VIRTUALENV || $+commands[virtualenv] )) && \
   # Disable the virtualenv prompt.
   VIRTUAL_ENV_DISABLE_PROMPT=1
 
+  venv_set=0
+
   if (( $+commands[pyenv] )); then
     if (( $+commands[pyenv-virtualenv-init] )); then
       eval "$(pyenv virtualenv-init -)"
+      venv_set=1
     fi
     if (( $#commands[(i)pyenv-virtualenvwrapper(_lazy|)] )); then
       pyenv "${${(@O)commands[(I)pyenv-virtualenvwrapper(_lazy|)]}[1]#pyenv-}"
+      venv_set=1
     fi
-  else
+  fi
+  if (( !(${venv_set}) )); then
     # Try 'virtualenvwrapper' without 'pyenv' wrapper in '$path' and other
     # known locations on a Debian based system.
     virtenv_sources=(
@@ -109,6 +114,7 @@ if (( $+VIRTUALENVWRAPPER_VIRTUALENV || $+commands[virtualenv] )) && \
     source "${virtenv_sources[1]}"
     unset virtenv_sources
   fi
+  unset venv_set
 fi
 
 # Load PIP completion.