[PORT] Fix code owners will not be mentioned when a pull request comes from a forked repository (gitea#30476)

Fix go-gitea#30277
Caused by go-gitea#29783

---

- Resolves go-gitea#5842
- Regression from go-gitea#2855

(cherry picked from commit c63060b)

Author: lunny

services/issue/pull.go

@@ -51,14 +51,14 @@ func PullRequestCodeOwnersReview(ctx context.Context, issue *issues_model.Issue,
 		return nil, err
 	}
 
-	if pr.HeadRepo.IsFork {
-		return nil, nil
-	}
-
 	if err := pr.LoadBaseRepo(ctx); err != nil {
 		return nil, err
 	}
 
+	if pr.BaseRepo.IsFork {
+		return nil, nil
+	}
+
 	repo, err := gitrepo.OpenRepository(ctx, pr.BaseRepo)
 	if err != nil {
 		return nil, err

tests/integration/pull_review_test.go

@@ -397,10 +397,18 @@ func TestPullView_CodeOwner(t *testing.T) {
 			require.NoError(t, err)
 
 			session := loginUser(t, "user5")
-			testPullCreate(t, session, "user5", "test_codeowner_fork", false, forkedRepo.DefaultBranch, "codeowner-basebranch-forked", "Test Pull Request2")
 
-			pr := unittest.AssertExistsAndLoadBean(t, &issues_model.PullRequest{BaseRepoID: repo.ID, HeadBranch: "codeowner-basebranch-forked"})
+			// create a pull request on the forked repository, code reviewers should not be mentioned
+			testPullCreateDirectly(t, session, "user5", "test_codeowner_fork", forkedRepo.DefaultBranch, "", "", "codeowner-basebranch-forked", "Test Pull Request on Forked Repository")
+
+			pr := unittest.AssertExistsAndLoadBean(t, &issues_model.PullRequest{BaseRepoID: forkedRepo.ID, HeadBranch: "codeowner-basebranch-forked"})
 			unittest.AssertExistsIf(t, false, &issues_model.Review{IssueID: pr.IssueID, Type: issues_model.ReviewTypeRequest, ReviewerID: 8})
+
+			// create a pull request to base repository, code reviewers should be mentioned
+			testPullCreateDirectly(t, session, repo.OwnerName, repo.Name, repo.DefaultBranch, forkedRepo.OwnerName, forkedRepo.Name, "codeowner-basebranch-forked", "Test Pull Request3")
+
+			pr = unittest.AssertExistsAndLoadBean(t, &issues_model.PullRequest{BaseRepoID: repo.ID, HeadRepoID: forkedRepo.ID, HeadBranch: "codeowner-basebranch-forked"})
+			unittest.AssertExistsIf(t, true, &issues_model.Review{IssueID: pr.IssueID, Type: issues_model.ReviewTypeRequest, ReviewerID: 8})
 		})
 	})
 }