修改《公共贴吧中，回复了帖子后，重新编辑的话能编辑标题》

Signed-off-by: alan <547533434@qq.com>

app/views/memos/edit.html.erb

@@ -1,5 +1,6 @@
 <!-- <h1>New memo</h1> -->
 <% @replying = !@memo.parent.nil? %>
+
 <h3><%=l(:label_memo_edit)%></h3>
 <%= labelled_form_for(@memo, :url => forum_memo_path(@memo.forum_id, @memo)) do |f|  %>
   <% if @memo.errors.any? %>
@@ -19,8 +20,12 @@
   <% end %>
   <div class="actions">
     <p>
-      <%= f.text_field :subject, :required => true, :size => 96 ,:readonly => @replying, :maxlength => 50%>
-    </p>
+      <% if @memo.parent.nil? && @memo.children.first.nil? %>
+         <%= f.text_field :subject, :required => true, :size => 96 ,:readonly => false,  :maxlength => 50%>
+      <% else %>
+          <%= f.text_field :subject, :required => true, :size => 96 ,:readonly => true, :style => "border: 1px solid gray", :maxlength => 50%>
+      <% end %>
+      </p>
     <% if User.current.admin?%>
         <p>
           <% unless @replying %>