Repo name added to automatically generated commit message when mergin… (#9997) (#10285)

* Repo name added to automatically generated commit message when merging pull request

* As per @lunny

Co-authored-by: Shashvat Kedia <sk261@snu.edu.in>
Co-authored-by: Lauris BH <lauris@nix.lv>

models/pull.go

@@ -180,7 +180,16 @@ func (pr *PullRequest) GetDefaultMergeMessage() string {
 			return ""
 		}
 	}
-	return fmt.Sprintf("Merge branch '%s' of %s/%s into %s", pr.HeadBranch, pr.MustHeadUserName(), pr.HeadRepo.Name, pr.BaseBranch)
+	if err := pr.LoadIssue(); err != nil {
+		log.Error("Cannot load issue %d for PR id %d: Error: %v", pr.IssueID, pr.ID, err)
+		return ""
+	}
+
+	if pr.BaseRepoID == pr.HeadRepoID {
+		return fmt.Sprintf("Merge pull request '%s' (#%d) from %s into %s", pr.Issue.Title, pr.Issue.Index, pr.HeadBranch, pr.BaseBranch)
+	}
+
+	return fmt.Sprintf("Merge pull request '%s' (#%d) from %s:%s into %s", pr.Issue.Title, pr.Issue.Index, pr.HeadRepo.FullName(), pr.HeadBranch, pr.BaseBranch)
 }
 
 // GetCommitMessages returns the commit messages between head and merge base (if there is one)