新增：创建文件对分支长度进行验证

app/forms/contents/create_form.rb

@@ -3,6 +3,8 @@ class Contents::CreateForm < BaseForm
 
   validates :filepath, presence: true
 
+  validates :branch, :new_branch, length: { maximum: 50 }
+
   validate :check_branch
 
   def check_branch