Post#tag_match: clean up read_only param.

* Drop /posts?ro=true param (broken).
* Clean up tag_match (rescuing PG::ConnectionBad didn't do anything, we
  just build the query here, we don't run it).

app/models/post.rb

@@ -1682,21 +1682,8 @@ class Post < ApplicationRecord
       where("posts.tag_index @@ to_tsquery('danbooru', E?)", tag.to_escaped_for_tsquery)
     end
 
-    def tag_match(query, read_only = false)
-      if query =~ /status:deleted.status:deleted/
-        # temp fix for degenerate crawlers
-        raise ActiveRecord::RecordNotFound
-      end
-
-      if read_only
-        begin
-          PostQueryBuilder.new(query, read_only: true).build
-        rescue PG::ConnectionBad
-          PostQueryBuilder.new(query).build
-        end
-      else
-        PostQueryBuilder.new(query).build
-      end
+    def tag_match(query, read_only: false)
+      PostQueryBuilder.new(query, read_only: read_only).build
     end
   end
   

app/models/saved_search.rb

@@ -97,7 +97,7 @@ class SavedSearch < ApplicationRecord
         CurrentUser.as_system do
           redis_key = "search:#{query}"
           return if redis.exists(redis_key)
-          post_ids = Post.tag_match(query, true).limit(QUERY_LIMIT).pluck(:id)
+          post_ids = Post.tag_match(query, read_only: true).limit(QUERY_LIMIT).pluck(:id)
           redis.sadd(redis_key, post_ids)
           redis.expire(redis_key, REDIS_EXPIRY)
         end