Required gitlab labels is subset of set labels

All labels in require.labels should be set on the change for the
pipeline to start

Change-Id: Ib3660a08dd7c72f9a7363587f9d1829bec92b8c2

releasenotes/notes/gitlab-require-labels-102a5885d3396417.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    The `labels` pipeline requirement in the `gitlab` driver erroneously treated
+    the labels as a boolean `or` but should have treated them as a boolean `and`
+    (i.e., all listed labels are required).
+    The behavior has been updated to match the documentation and other drivers.

tests/fixtures/layouts/requirements-gitlab.yaml

@@ -42,7 +42,9 @@
     manager: independent
     require:
       gitlab:
-        labels: gateit
+        labels:
+          - gateit
+          - another_label
     trigger:
       gitlab:
         - event: gl_merge_request
@@ -89,4 +91,4 @@
     name: org/project3
     label-check:
       jobs:
-        - project3-test
+        - project3-test

tests/unit/test_gitlab_driver.py

@@ -641,6 +641,12 @@ class TestGitlabDriver(ZuulTestCase):
 
         A.labels = ['gateit', 'prio:low']
 
+        self.fake_gitlab.emitEvent(A.getMergeRequestUpdatedEvent())
+        self.waitUntilSettled()
+        self.assertEqual(0, len(self.history))
+
+        A.labels = ['gateit', 'prio:low', 'another_label']
+
         self.fake_gitlab.emitEvent(A.getMergeRequestUpdatedEvent())
         self.waitUntilSettled()
         self.assertEqual(1, len(self.history))

zuul/driver/gitlab/gitlabmodel.py

@@ -264,7 +264,7 @@ class GitlabRefFilter(RefFilter):
                 return False
 
         if self.labels:
-            if not set(change.labels).intersection(set(self.labels)):
+            if not set(self.labels).issubset(set(change.labels)):
                 return False
 
         return True