Fix `serial?` with quoted sequence name

activerecord/lib/active_record/connection_adapters/postgresql/column.rb

@@ -8,7 +8,8 @@ class PostgreSQLColumn < Column #:nodoc:
       def serial?
         return unless default_function
 
-        %r{\Anextval\('(?<table_name>.+)_#{name}_seq'::regclass\)\z} === default_function
+        table_name = @table_name || '(?<table_name>.+)'
+        %r{\Anextval\('"?#{table_name}_#{name}_seq"?'::regclass\)\z} === default_function
       end
     end
   end

activerecord/test/cases/primary_keys_test.rb

@@ -175,6 +175,14 @@ def test_primary_key_update_with_custom_key_name
     dashboard = Dashboard.first
     assert_equal '2', dashboard.id
   end
+
+  if current_adapter?(:PostgreSQLAdapter)
+    def test_serial_with_quoted_sequence_name
+      column = MixedCaseMonkey.columns_hash[MixedCaseMonkey.primary_key]
+      assert_equal "nextval('\"mixed_case_monkeys_monkeyID_seq\"'::regclass)", column.default_function
+      assert column.serial?
+    end
+  end
 end
 
 class PrimaryKeyWithNoConnectionTest < ActiveRecord::TestCase