Do not fetch all refs (#7797)

Which would unnecessarily slow down the pull compare operation.

modules/git/repo_compare.go

@@ -54,7 +54,7 @@ func (repo *Repository) GetCompareInfo(basePath, baseBranch, headBranch string)
 	if repo.Path != basePath {
 		// Add a temporary remote
 		tmpRemote = strconv.FormatInt(time.Now().UnixNano(), 10)
-		if err = repo.AddRemote(tmpRemote, basePath, true); err != nil {
+		if err = repo.AddRemote(tmpRemote, basePath, false); err != nil {
 			return nil, fmt.Errorf("AddRemote: %v", err)
 		}
 		defer func() {