Add new tests to presubmit, fix errors

go/login/login.go

Index: go/login/login.go
diff --git a/go/login/login.go b/go/login/login.go
index a6dd0f753dbb12d68f050dba3c797e01d4b31edf..7a744e84fff3b6a866c9faed1bcbc8965266b492 100644
--- a/go/login/login.go
+++ b/go/login/login.go
@@ -262,6 +262,6 @@ func StatusHandler(w http.ResponseWriter, r *http.Request) {
 		"LoginURL": LoginURL(w, r),
 	}
 	if err := enc.Encode(body); err != nil {
-		glog.Errorf("Failed to encode Login status to JSON", err)
+		glog.Errorf("Failed to encode Login status to JSON: %s", err)
 	}
 }