Convert boolean strings from set_fact to proper boolean values

Also adds integration tests for booleanification of strings

Fixes #8629

test/integration/roles/test_conditionals/tasks/main.yml

@@ -193,3 +193,77 @@
   assert:
     that:
     - "result.skipped == true"
+
+#-----------------------------------------------------------------------
+# proper booleanification tests (issue #8629)
+
+- name: set fact to string 'false'
+  set_fact: bool_test1=false
+
+- name: set fact to string 'False'
+  set_fact: bool_test2=False
+
+- name: set fact to a proper boolean using complex args
+  set_fact:
+    bool_test3: false
+
+- name: "test boolean value 'false' string using 'when: var'"
+  command: echo 'hi'
+  when: bool_test1
+  register: result
+
+- name: assert that the task did not run for 'false'
+  assert:
+    that:
+    - "result.skipped == true"
+
+- name: "test boolean value 'false' string using 'when: not var'"
+  command: echo 'hi'
+  when: not bool_test1
+  register: result
+
+- name: assert that the task DID run for not 'false'
+  assert:
+    that:
+    - "result.changed"
+
+- name: "test boolean value of 'False' string using 'when: var'"
+  command: echo 'hi'
+  when: bool_test2
+  register: result
+
+- name: assert that the task did not run for 'False'
+  assert:
+    that:
+    - "result.skipped == true"
+
+- name: "test boolean value 'False' string using 'when: not var'"
+  command: echo 'hi'
+  when: not bool_test2
+  register: result
+
+- name: assert that the task DID run for not 'False'
+  assert:
+    that:
+    - "result.changed"
+
+- name: "test proper boolean value of complex arg using 'when: var'"
+  command: echo 'hi'
+  when: bool_test3
+  register: result
+
+- name: assert that the task did not run for proper boolean false
+  assert:
+    that:
+    - "result.skipped == true"
+
+- name: "test proper boolean value of complex arg using 'when: not var'"
+  command: echo 'hi'
+  when: not bool_test3
+  register: result
+
+- name: assert that the task DID run for not false
+  assert:
+    that:
+    - "result.changed"
+