gitlab: Begin migrating owned to default to True

Per discussion in GothenburgBitFactory#986, this has a few benefits:

- Our example configuration will actually be valid since it uses
gitlab.com as a host but does not define a filter.
- More similar default behavior to other services, such as github.
- Hopefully less confusion about the filtering requirements to
avoid rate-banning and fewer bug reports caused by rate bans.

We start off by implementing the first step, which is to raise a
warning if 'owned' is undefined. The remainder of the migration plan is
in the validator docstring.

bugwarrior/services/gitlab.py

@@ -29,7 +29,7 @@ class GitlabConfig(config.ServiceConfig):
     include_regex: typing.Optional[typing.Pattern] = None
     exclude_regex: typing.Optional[typing.Pattern] = None
     membership: bool = False
-    owned: bool = False
+    owned: typing.Optional[bool] = None
     import_labels_as_tags: bool = False
     label_template: str = '{{label}}'
     include_merge_requests: typing.Union[bool, typing_extensions.Literal['Undefined']] = 'Undefined'
@@ -99,6 +99,23 @@ def filter_gitlab_dot_com(cls, values):
                 "there are too many on gitlab.com to fetch them all.")
         return values
 
+    @pydantic.validator('owned', always=True)
+    def require_owned(cls, v):
+        """
+        Migrate 'owned' field from default False to default True.
+
+        Migration plan:
+            - [X] Warning if 'owned' is undefined.
+            - [ ] Next major version: validation error if 'owned' is undefined.
+            - [ ] Subsequent major version: 'owned' defaults to True.
+        """
+        if v is None:
+            log.warning(
+                "WARNING: Gitlab's 'owned' configuration field should be set "
+                "explicitly. In a future release, this will be an error.")
+            v = False
+        return v
+
 
 class GitlabClient(ServiceClient):
     """Abstraction of Gitlab API v4"""

tests/config/test_schema.py

@@ -77,6 +77,7 @@ def setUp(self):
             'host': 'my-git.org',
             'login': 'arbitrary_login',
             'token': 'arbitrary_token',
+            'owned': 'false',
         }
 
     def test_valid(self):

tests/test_gitlab.py

@@ -599,6 +599,16 @@ def test_body_no_limit(self):
         issue = dict(description="A very short issue body.  Fixes #42.")
         self.assertEqual(issue["description"], self.service.description(issue))
 
+    def test_undefined_owned_warning(self):
+        self.config['myservice'].pop('owned')
+        self.config['myservice']['membership'] = 'true'
+        self.validate()
+        self.assertEqual(len(self.caplog.records), 1)
+        self.assertIn(
+            "WARNING: Gitlab's 'owned' configuration field should be set "
+            "explicitly. In a future release, this will be an error.",
+            self.caplog.records[0].message)
+
 
 class TestGitlabIssue(AbstractServiceTest, ServiceTest):
     maxDiff = None