save defaultBranch we looked up for the timestamp lookup

server/upstream/helper.go

@@ -35,6 +35,7 @@ func GetBranchTimestamp(owner, repo, branch, giteaRoot, giteaAPIToken string, br
 			return nil
 		}
 		result.Branch = defaultBranch
+		branch = defaultBranch
 	}
 
 	timestamp, err := giteaGetRepoBranchTimestamp(giteaRoot, owner, repo, branch, giteaAPIToken)