Make sure that we pass list in loop

map returns a generator that needs to be converted to a list for
the loop.

We also don't need unique as this is iterating over a list of
directory names that must already be unique.

Change-Id: Ibd22d79be29aaa9d3a7924319c59929e665f9cbc

roles/ensure-python/tasks/stow.yaml

@@ -7,7 +7,7 @@
 
 - name: Activate stow
   command: "stow -d {{ python_stow_dir }} -S {{ zj_stow_env | basename }}"
-  loop: "{{ stow_envs.files | map(attribute='path') | unique }}"
+  loop: "{{ stow_envs.files | map(attribute='path') | list }}"
   loop_control:
     loop_var: zj_stow_env
   when: python_version in item