ensure-twine: Avoid Reinstalling twine if present

On a static node where twine isn't present in the PATH, twine would be
always reinstalled even if already present in venv because it's not checked.

This patch adds twine pip check, the first matching line is used to get
executable path

Change-Id: I2c972147269bf717c30f093975ca6349bed68fbe

roles/ensure-twine/tasks/main.yaml

@@ -1,6 +1,6 @@
 - name: Check for twine install
   shell: |
-    command -v {{ twine_executable }} || exit 1
+    command -v {{ twine_executable }} ~/.local/bin/twine || exit 1
   args:
     executable: /bin/bash
   failed_when: false
@@ -8,7 +8,7 @@
 
 - name: Set pypi_twine_executable
   set_fact:
-    pypi_twine_executable: "{{ register_twine.stdout }}"
+    pypi_twine_executable: "{{ register_twine.stdout_lines[0] }}"
   when: register_twine.rc == 0
 
 - name: Ensure twine is installed