Move tox logs into env specific dirs

New tox>=4 does not prefix the filenames with the env name. THis means
we'll squash together log files if more than one env is run. Address
this while on tox v3 to avoid regressions.

Change-Id: I2601cc7faa1f7a5d7f2d950d637dfa84c50717ae

roles/fetch-tox-output/tasks/main.yaml

@@ -64,7 +64,7 @@
 
 - name: Copy tox logs  # noqa risky-file-permissions
   copy:
-    dest: "{{ zuul_output_dir }}/logs/tox/"
+    dest: "{{ zuul_output_dir }}/logs/tox/{{ zj_testenv }}/"
     src: "{{ zuul_work_dir }}/.tox/{{ zj_testenv }}/log/"
     remote_src: true
   loop: "{{ envlist }}"
@@ -77,7 +77,7 @@
 
 - name: Collect tox logs
   synchronize:
-    dest: "{{ log_path }}"
+    dest: "{{ log_path }}/{{ zj_testenv }}"
     mode: pull
     src: "{{ zuul_work_dir }}/.tox/{{ zj_testenv }}/log/"
     verify_host: true

test-playbooks/python/fetch-tox-output.yaml

@@ -56,14 +56,14 @@
   post_tasks:
     - name: Check for artifact on the test instance
       stat:
-        path: "{{ ansible_user_dir }}/zuul-output/logs/tox/venv-0.log"
+        path: "{{ ansible_user_dir }}/zuul-output/logs/tox/venv/venv-0.log"
       register: _test_artifact
       failed_when: not _test_artifact.stat.exists
       when: zuul_use_fetch_output
 
     - name: Check for artifact on the executor
       stat:
-        path: "{{ zuul.executor.log_root }}/tox/venv-0.log"
+        path: "{{ zuul.executor.log_root }}/tox/venv/venv-0.log"
       delegate_to: localhost
       register: _executor_artifact
       failed_when: not _executor_artifact.stat.exists