iss-1272: Fix concurrent writes when rendering html templates in ui (#1280)

Author: lx223

pkg/ui/ui.go

@@ -75,9 +75,9 @@ func (bu *BaseUI) executeTemplate(w http.ResponseWriter, name string, prefix str
 		return
 	}
 
-	bu.tmplFuncs["pathPrefix"] = func() string { return prefix }
-
-	t, err := template.New("").Funcs(bu.tmplFuncs).Parse(text)
+	t, err := template.New("").Funcs(bu.tmplFuncs).
+		Funcs(template.FuncMap{"pathPrefix": func() string { return prefix }}).
+		Parse(text)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return