posts: fix incorrect post counts for -pool:, -fav: searches

Fix `-pool:1234` and `-fav:evazion` searches incorrectly returning the
same post count as `pool:1234` and `fav:evazion` searches.

app/logical/post_query.rb

@@ -111,12 +111,12 @@ class PostQuery
     ast.none?
   end
 
-  # True if the search is a single metatag search for the given metatag.
+  # True if the search is a single, non-negated metatag search for the given metatag. Assumes the query has been normalized.
   def is_metatag?(name, value = nil)
     if value.nil?
-      is_single_term? && has_metatag?(name)
+      metatag? && has_metatag?(name)
     else
-      is_single_term? && find_metatag(name) == value.to_s
+      metatag? && find_metatag(name) == value.to_s
     end
   end
 

test/unit/post_query_builder_test.rb

@@ -1480,14 +1480,21 @@ class PostQueryBuilderTest < ActiveSupport::TestCase
 
         assert_fast_count(3, "pool:#{pool.id}")
         assert_fast_count(3, "pool:#{pool.name}")
+        assert_fast_count(3, "ordpool:#{pool.id}")
+        assert_fast_count(3, "ordpool:#{pool.name}")
+
+        assert_fast_count(Post.count, "-pool:#{pool.id}")
+        assert_fast_count(Post.count, "-pool:#{pool.name}")
       end
 
       should "return the correct favorite count for a fav:<name> search" do
         fav = create(:favorite)
-        fav.user.update!(favorite_count: 1)
+        User.where(id: fav.user).update_all(favorite_count: 42) # XXX favorite_count is readonly; update it this way to bypass the readonly check.
 
-        assert_fast_count(1, "fav:#{fav.user.name}")
-        assert_fast_count(1, "ordfav:#{fav.user.name}")
+        assert_fast_count(42, "fav:#{fav.user.name}")
+        assert_fast_count(42, "ordfav:#{fav.user.name}")
+
+        assert_fast_count(1, "-fav:#{fav.user.name}")
       end
 
       should "return the correct favorite count for a fav:<name> search for a user with private favorites" do