library: fix bug in radosgw_zone.py

If for some reason `get_zonegroup()` returns a failure, we must handle
and make the module exit properly instead of failing with the following
python trace:

```
Traceback (most recent call last):
  File "./AnsiballZ_radosgw_zone.py", line 247, in <module>
    _ansiballz_main()
  File "./AnsiballZ_radosgw_zone.py", line 234, in _ansiballz_main
    exitcode = debug(sys.argv[1], zipped_mod, ANSIBALLZ_PARAMS)
  File "./AnsiballZ_radosgw_zone.py", line 202, in debug
    runpy.run_module(mod_name='ansible.modules.radosgw_zone', init_globals=None, run_name='__main__', alter_sys=True)
  File "/usr/lib64/python3.6/runpy.py", line 205, in run_module
    return _run_module_code(code, init_globals, run_name, mod_spec)
  File "/usr/lib64/python3.6/runpy.py", line 96, in _run_module_code
    mod_name, mod_spec, pkg_name, script_name)
  File "/usr/lib64/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/vagrant/.ansible/tmp/ansible-tmp-1610728441.41-685133-218973990589597/debug_dir/ansible/modules/radosgw_zone.py", line 467, in <module>
    main()
  File "/home/vagrant/.ansible/tmp/ansible-tmp-1610728441.41-685133-218973990589597/debug_dir/ansible/modules/radosgw_zone.py", line 463, in main
    run_module()
  File "/home/vagrant/.ansible/tmp/ansible-tmp-1610728441.41-685133-218973990589597/debug_dir/ansible/modules/radosgw_zone.py", line 425, in run_module
    zonegroup = json.loads(_out)
  File "/usr/lib64/python3.6/json/__init__.py", line 354, in loads
    return _default_decoder.decode(s)
  File "/usr/lib64/python3.6/json/decoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib64/python3.6/json/decoder.py", line 357, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

```

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>

library/radosgw_zone.py

@@ -16,6 +16,10 @@
 __metaclass__ = type
 
 from ansible.module_utils.basic import AnsibleModule
+try:
+    from ansible.module_utils.ca_common import fatal
+except ImportError:
+    from module_utils.ca_common import fatal
 import datetime
 import json
 import os
@@ -412,24 +416,27 @@ def run_module():
         if rc == 0:
             zone = json.loads(out)
             _rc, _cmd, _out, _err = exec_commands(module, get_zonegroup(module, container_image=container_image))
-            zonegroup = json.loads(_out)
-            if not access_key:
-                access_key = ''
-            if not secret_key:
-                secret_key = ''
-            current = {
-                'endpoints': next(zone['endpoints'] for zone in zonegroup['zones'] if zone['name'] == name),
-                'access_key': zone['system_key']['access_key'],
-                'secret_key': zone['system_key']['secret_key']
-            }
-            asked = {
-                'endpoints': endpoints,
-                'access_key': access_key,
-                'secret_key': secret_key
-            }
-            if current != asked:
-                rc, cmd, out, err = exec_commands(module, modify_zone(module, container_image=container_image))
-                changed = True
+            if _rc == 0:
+                zonegroup = json.loads(_out)
+                if not access_key:
+                    access_key = ''
+                if not secret_key:
+                    secret_key = ''
+                current = {
+                    'endpoints': next(zone['endpoints'] for zone in zonegroup['zones'] if zone['name'] == name),
+                    'access_key': zone['system_key']['access_key'],
+                    'secret_key': zone['system_key']['secret_key']
+                }
+                asked = {
+                    'endpoints': endpoints,
+                    'access_key': access_key,
+                    'secret_key': secret_key
+                }
+                if current != asked:
+                    rc, cmd, out, err = exec_commands(module, modify_zone(module, container_image=container_image))
+                    changed = True
+            else:
+                fatal(_err, module)
         else:
             rc, cmd, out, err = exec_commands(module, create_zone(module, container_image=container_image))
             changed = True