Display pull request head branch even the branch deleted or repository deleted (#10413)

* Display pull request head branch even the branch deleted or repository deleted

* Merge getHeadRepo/loadHeadRepo and getBaseRepo/loadBaseRepo on pull and fill repo when pr.Issue.Repo is available

* retrieve sha from pull head when pull request branch deleted and fix tests

* Fix test

* Ensure MustHeadRepoName returns empty string if no head repo

Co-authored-by: zeripath <art27@cantab.net>

4 files changed, 25 insertions, 30 deletions

diff --git a/services/pull/merge.go b/services/pull/merge.go
index 4d02d7193d..c8351ba85a 100644
--- a/services/pull/merge.go
+++ b/services/pull/merge.go
@@ -33,13 +33,12 @@ import (
 // Caller should check PR is ready to be merged (review and status checks)
 // FIXME: add repoWorkingPull make sure two merges does not happen at same time.
 func Merge(pr *models.PullRequest, doer *models.User, baseGitRepo *git.Repository, mergeStyle models.MergeStyle, message string) (err error) {
-
-	if err = pr.GetHeadRepo(); err != nil {
-		log.Error("GetHeadRepo: %v", err)
-		return fmt.Errorf("GetHeadRepo: %v", err)
-	} else if err = pr.GetBaseRepo(); err != nil {
-		log.Error("GetBaseRepo: %v", err)
-		return fmt.Errorf("GetBaseRepo: %v", err)
+	if err = pr.LoadHeadRepo(); err != nil {
+		log.Error("LoadHeadRepo: %v", err)
+		return fmt.Errorf("LoadHeadRepo: %v", err)
+	} else if err = pr.LoadBaseRepo(); err != nil {
+		log.Error("LoadBaseRepo: %v", err)
+		return fmt.Errorf("LoadBaseRepo: %v", err)
 	}
 
 	prUnit, err := pr.BaseRepo.GetUnit(models.UnitTypePullRequests)
@@ -535,18 +534,15 @@ func IsUserAllowedToMerge(pr *models.PullRequest, p models.Permission, user *mod
 
 // CheckPRReadyToMerge checks whether the PR is ready to be merged (reviews and status checks)
 func CheckPRReadyToMerge(pr *models.PullRequest) (err error) {
-	if pr.BaseRepo == nil {
-		if err = pr.GetBaseRepo(); err != nil {
-			return fmt.Errorf("GetBaseRepo: %v", err)
-		}
+	if err = pr.LoadBaseRepo(); err != nil {
+		return fmt.Errorf("LoadBaseRepo: %v", err)
+	}
+
+	if err = pr.LoadProtectedBranch(); err != nil {
+		return fmt.Errorf("LoadProtectedBranch: %v", err)
 	}
 	if pr.ProtectedBranch == nil {
-		if err = pr.LoadProtectedBranch(); err != nil {
-			return fmt.Errorf("LoadProtectedBranch: %v", err)
-		}
-		if pr.ProtectedBranch == nil {
-			return nil
-		}
+		return nil
 	}
 
 	isPass, err := IsPullCommitStatusPass(pr)
diff --git a/services/pull/pull.go b/services/pull/pull.go
index 6af751856d..5c7ec91f5d 100644
--- a/services/pull/pull.go
+++ b/services/pull/pull.go
@@ -236,16 +236,15 @@ func AddTestPullRequestTask(doer *models.User, repoID int64, branch string, isSy
 // checkIfPRContentChanged checks if diff to target branch has changed by push
 // A commit can be considered to leave the PR untouched if the patch/diff with its merge base is unchanged
 func checkIfPRContentChanged(pr *models.PullRequest, oldCommitID, newCommitID string) (hasChanged bool, err error) {
-
-	if err = pr.GetHeadRepo(); err != nil {
-		return false, fmt.Errorf("GetHeadRepo: %v", err)
+	if err = pr.LoadHeadRepo(); err != nil {
+		return false, fmt.Errorf("LoadHeadRepo: %v", err)
 	} else if pr.HeadRepo == nil {
 		// corrupt data assumed changed
 		return true, nil
 	}
 
-	if err = pr.GetBaseRepo(); err != nil {
-		return false, fmt.Errorf("GetBaseRepo: %v", err)
+	if err = pr.LoadBaseRepo(); err != nil {
+		return false, fmt.Errorf("LoadBaseRepo: %v", err)
 	}
 
 	headGitRepo, err := git.OpenRepository(pr.HeadRepo.RepoPath())
diff --git a/services/pull/review.go b/services/pull/review.go
index 2b7c9e8646..25e0ca858a 100644
--- a/services/pull/review.go
+++ b/services/pull/review.go
@@ -111,8 +111,8 @@ func createCodeComment(doer *models.User, repo *models.Repository, issue *models
 		return nil, fmt.Errorf("GetPullRequestByIssueID: %v", err)
 	}
 	pr := issue.PullRequest
-	if err := pr.GetBaseRepo(); err != nil {
-		return nil, fmt.Errorf("GetHeadRepo: %v", err)
+	if err := pr.LoadBaseRepo(); err != nil {
+		return nil, fmt.Errorf("LoadHeadRepo: %v", err)
 	}
 	gitRepo, err := git.OpenRepository(pr.BaseRepo.RepoPath())
 	if err != nil {
diff --git a/services/pull/temp_repo.go b/services/pull/temp_repo.go
index bb6ce2921e..ffac92ade5 100644
--- a/services/pull/temp_repo.go
+++ b/services/pull/temp_repo.go
@@ -17,17 +17,17 @@ import (
 )
 
 func createTemporaryRepo(pr *models.PullRequest) (string, error) {
-	if err := pr.GetHeadRepo(); err != nil {
-		log.Error("GetHeadRepo: %v", err)
-		return "", fmt.Errorf("GetHeadRepo: %v", err)
+	if err := pr.LoadHeadRepo(); err != nil {
+		log.Error("LoadHeadRepo: %v", err)
+		return "", fmt.Errorf("LoadHeadRepo: %v", err)
 	} else if pr.HeadRepo == nil {
 		log.Error("Pr %d HeadRepo %d does not exist", pr.ID, pr.HeadRepoID)
 		return "", &models.ErrRepoNotExist{
 			ID: pr.HeadRepoID,
 		}
-	} else if err := pr.GetBaseRepo(); err != nil {
-		log.Error("GetBaseRepo: %v", err)
-		return "", fmt.Errorf("GetBaseRepo: %v", err)
+	} else if err := pr.LoadBaseRepo(); err != nil {
+		log.Error("LoadBaseRepo: %v", err)
+		return "", fmt.Errorf("LoadBaseRepo: %v", err)
 	} else if pr.BaseRepo == nil {
 		log.Error("Pr %d BaseRepo %d does not exist", pr.ID, pr.BaseRepoID)
 		return "", &models.ErrRepoNotExist{