Attempt to copy the coverage report even if job fails

Some cover jobs such as the one in openstack/manila [1]
run custom coverage jobs and zuul_success=false doesn't
always mean that the 'coverage' tool itself has failed
to run.

So, attempt to copy the coverage report if it exists.

[1] http://git.openstack.org/cgit/openstack/manila/tree/tools/cover.sh

Change-Id: I5487f8c6ba8185fa0bfe7d83d24df3e065e0a903

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

@@ -1,20 +1,19 @@
-- when: zuul_success | default(true) | bool
-  block:
+- name: Check to see if coverage report exists
+  stat:
+    path: "{{ coverage_output_src }}"
+    register: coverage_report_stat
 
-    - name: Check to see if coverage report exists
-      stat:
-        path: "{{ coverage_output_src }}"
-      register: coverage_report_stat
+- when:
+    - zuul_success | default(true) | bool
+    - not coverage_report_stat.stat.exists
+  name: Fail if coverage job succeeded and report is not present
+  fail:
+    msg: "Coverage report was not found even though tests succeeded"
 
-    - name: Collect coverage details output
-      synchronize:
-        dest: "{{ zuul_executor_dest }}"
-        mode: pull
-        src: "{{ coverage_output_src }}"
-        verify_host: true
-      when: coverage_report_stat.stat.exists
-
-    - name: Fail if coverage report not found
-      fail:
-        msg: "Coverage report was not found even though tests succeeded"
-      when: not coverage_report_stat.stat.exists
+- when: coverage_report_stat.stat.exists
+  name: Collect coverage details output
+  synchronize:
+    dest: "{{ zuul_executor_dest }}"
+    mode: pull
+    src: "{{ coverage_output_src }}"
+    verify_host: true