use overwrite semantics for remote file distributor

app/logical/remote_file_manager.rb

@@ -18,8 +18,9 @@ class RemoteFileManager
           ftp.rename!(temp_path, path)
         rescue Net::SFTP::StatusException
           # this typically means the file already exists
-          # so just clean up
-          ftp.remove(temp_path)
+          # so delete and try renaming again
+          ftp.remove!(path)
+          ftp.rename!(temp_path, path)
         end
       end
     end

app/views/posts/partials/index/_missed_search_count.html.erb

@@ -1,7 +1,7 @@
 <script type="text/javascript">
   $(function() {
     var tags = $("#tags").val();
-    if (Danbooru.get_url_parameter("ms") === "1" && tags && tags.length > 0 && $(".post-preview").size() < 10) {
+    if (Danbooru.get_url_parameter("ms") === "1" && tags && tags.length > 0 && $(".post-preview").size() === 0) {
       $.post("<%= Danbooru.config.report_server %>/missed_searches", {
         session_id: "<%= session_id %>",
         tags: $("#tags").val(),