Add comments explaining json_query()

Signed-off-by: Vaclav Dolezal <vdolezal@redhat.com>

Author: yontalcar

tasks/main-blivet.yml

@@ -51,6 +51,8 @@
 
 - name: Apply defaults to pools and volumes [4/6]
   set_fact:
+    # json_query(...) used instead of "|selectattr('pool', 'equalto', item.name)|list"
+    # as that expression wouldn't work with Jinja versions <2.8
     _storage_vols_no_defaults_by_pool: "{{ _storage_vols_no_defaults_by_pool|default({})|
                                         combine({item.name: _storage_vols_w_defaults|json_query('[?pool==`\"{}\"`]'.format(item.name))}) }}"
   loop: "{{ _storage_pools }}"

tests/test-verify-volume-mount.yml

@@ -1,6 +1,8 @@
 ---
 - name: Set some facts
   set_fact:
+    # json_query(...) used instead of "|selectattr('device', 'equalto', storage_test_volume._device)|list"
+    # as that expression wouldn't work with Jinja versions <2.8
     storage_test_mount_device_matches: "{{ ansible_mounts|json_query('[?device==`\"{}\"`]'.format(storage_test_volume._device))}}"
     storage_test_mount_point_matches: "{{ ansible_mounts|json_query('[?mount==`\"{}\"`]'.format(storage_test_volume.mount_point))}}"
     storage_test_mount_expected_match_count: "{{ 1 if _storage_test_volume_present and storage_test_volume.mount_point else 0 }}"