Do not fail when a certain python version is not available

When a tobiko test step fails because it requires a python version that
is not available, the result should not be failed

Change-Id: I1b1ab5d005d75319873610b03c85b02c8824c202

roles/tobiko-ensure-python3/tasks/install.yaml

@@ -21,6 +21,11 @@
     - compile_python3 | bool
 
 
+- name: "initialize found_python_version"
+  set_fact:
+    found_python_version: false
+
+
 - name: "get '{{ python_command }}' full path"
   shell: |
     export PATH={{ python_exe_path }}
@@ -29,6 +34,11 @@
   changed_when: no
 
 
+- name: "update found_python_version"
+  set_fact:
+    found_python_version: true
+
+
 - name: "get '{{ get_python_exe.stdout_lines | first }}' info"
   script:
     cmd: get_python_info.py --base --quiet

roles/tobiko-run/tasks/run.yaml

@@ -24,6 +24,7 @@
     - name: "add step failure: '{{ tox_step_name }}'"
       set_fact:
         test_step_failures: '{{ test_step_failures + [test_step] }}'
+      when: 'found_python_version is not defined or found_python_version == true'
 
     - name: "abort execution at first failure"
       debug: var=test_step