Various Merge Base fixes (#10786)

* Fix broken merge base migration v128 for merged PR

* Allow PRs with deleted base branches to still show diff

* as per @lunny

Co-authored-by: Lauris BH <lauris@nix.lv>

1 files changed, 34 insertions, 4 deletions

diff --git a/routers/repo/pull.go b/routers/repo/pull.go
index 5fb5bfa2bb..c29cfb81b2 100644
--- a/routers/repo/pull.go
+++ b/routers/repo/pull.go
@@ -308,7 +308,6 @@ func PrepareMergedViewPullInfo(ctx *context.Context, issue *models.Issue) *git.C
 
 	compareInfo, err := ctx.Repo.GitRepo.GetCompareInfo(ctx.Repo.Repository.RepoPath(),
 		pull.MergeBase, pull.GetGitRefName())
-
 	if err != nil {
 		if strings.Contains(err.Error(), "fatal: Not a valid object name") {
 			ctx.Data["IsPullRequestBroken"] = true
@@ -360,9 +359,40 @@ func PrepareViewPullInfo(ctx *context.Context, issue *models.Issue) *git.Compare
 		ctx.Data["IsPullRequestBroken"] = true
 		ctx.Data["BaseTarget"] = pull.BaseBranch
 		ctx.Data["HeadTarget"] = pull.HeadBranch
-		ctx.Data["NumCommits"] = 0
-		ctx.Data["NumFiles"] = 0
-		return nil
+
+		sha, err := baseGitRepo.GetRefCommitID(pull.GetGitRefName())
+		if err != nil {
+			ctx.ServerError(fmt.Sprintf("GetRefCommitID(%s)", pull.GetGitRefName()), err)
+			return nil
+		}
+		commitStatuses, err := models.GetLatestCommitStatus(repo, sha, 0)
+		if err != nil {
+			ctx.ServerError("GetLatestCommitStatus", err)
+			return nil
+		}
+		if len(commitStatuses) > 0 {
+			ctx.Data["LatestCommitStatuses"] = commitStatuses
+			ctx.Data["LatestCommitStatus"] = models.CalcCommitStatus(commitStatuses)
+		}
+
+		compareInfo, err := baseGitRepo.GetCompareInfo(pull.BaseRepo.RepoPath(),
+			pull.MergeBase, pull.GetGitRefName())
+		if err != nil {
+			if strings.Contains(err.Error(), "fatal: Not a valid object name") {
+				ctx.Data["IsPullRequestBroken"] = true
+				ctx.Data["BaseTarget"] = pull.BaseBranch
+				ctx.Data["NumCommits"] = 0
+				ctx.Data["NumFiles"] = 0
+				return nil
+			}
+
+			ctx.ServerError("GetCompareInfo", err)
+			return nil
+		}
+
+		ctx.Data["NumCommits"] = compareInfo.Commits.Len()
+		ctx.Data["NumFiles"] = compareInfo.NumFiles
+		return compareInfo
 	}
 
 	var headBranchExist bool