fix(bot): don't attempt merge on changes requested (#765)

A regression was introduced with #762 that caused the bot to attempt to update pull requests when changes were requested. This change fixes that issue.

related #761

bot/kodiak/evaluation.py

@@ -839,6 +839,10 @@ async def set_status(msg: str, markdown_content: Optional[str] = None) -> None:
             await block_merge(api, pull_request, "missing required reviews")
             return
 
+        if pull_request.reviewDecision == PullRequestReviewDecision.CHANGES_REQUESTED:
+            await block_merge(api, pull_request, "changes requested")
+            return
+
         if (
             branch_protection.requiresConversationResolution
             and pull_request.reviewThreads.nodes is not None

bot/kodiak/tests/evaluation/test_branch_protection.py

@@ -209,6 +209,32 @@ async def test_mergeable_missing_required_review() -> None:
     assert api.queue_for_merge.called is False
 
 
+@pytest.mark.asyncio
+async def test_mergeable_missing_changes_requested() -> None:
+    """
+    Don't merge when a changes requested.
+    """
+    api = create_api()
+    mergeable = create_mergeable()
+    pull_request = create_pull_request()
+
+    pull_request.mergeStateStatus = MergeStateStatus.BEHIND
+    pull_request.reviewDecision = PullRequestReviewDecision.CHANGES_REQUESTED
+
+    await mergeable(
+        api=api,
+        pull_request=pull_request,
+    )
+    assert api.set_status.call_count == 1
+    assert api.dequeue.call_count == 1
+    assert "changes requested" in api.set_status.calls[0]["msg"]
+
+    # verify we haven't tried to update/merge the PR
+    assert api.update_branch.called is False
+    assert api.merge.called is False
+    assert api.queue_for_merge.called is False
+
+
 @pytest.mark.asyncio
 async def test_mergeable_update_branch_immediately() -> None:
     """