fixed 删除用户时issue，pr用户显示已注销

app/views/pull_requests/show.json.jbuilder

@@ -46,7 +46,7 @@ json.issue do
   json.assign_user_login @issue_assign_to.try(:login)
   json.author_name @issue_user.blank?? "已注销": @issue_user.show_real_name
   json.author_login @issue_user.try(:login)
-  json.avatar_url @issue_user.blank?? User::Avatar.get_letter_avatar_url("D") : url_to_avatar(@issue_user)
+  json.author_picture @issue_user.blank?? User::Avatar.get_letter_avatar_url("D") : url_to_avatar(@issue_user)
   json.issue_status @issue.issue_status.try(:name)
   json.priority @issue.priority.try(:name)
   json.version @issue.version.try(:name)