Fix that unsigned with zerofill is treated as signed

Fixes #27125.

activerecord/CHANGELOG.md

+*   Fix that unsigned with zerofill is treated as signed.
+
+    Fixes #27125.
+
+    *Ryuta Kamizono*
+
 *   Fix the uniqueness validation scope with a polymorphic association.
 
     *Sergey Alekseev*

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -693,7 +693,7 @@ def initialize_type_map(m) # :nodoc:
 
         def register_integer_type(mapping, key, options) # :nodoc:
           mapping.register_type(key) do |sql_type|
-            if /\bunsigned\z/.match?(sql_type)
+            if /\bunsigned\b/.match?(sql_type)
               Type::UnsignedInteger.new(options)
             else
               Type::Integer.new(options)

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

@@ -5,7 +5,7 @@ class Column < ConnectionAdapters::Column # :nodoc:
         delegate :extra, to: :sql_type_metadata, allow_nil: true
 
         def unsigned?
-          /\bunsigned\z/.match?(sql_type)
+          !/\A(?:enum|set)\b/.match?(sql_type) && /\bunsigned\b/.match?(sql_type)
         end
 
         def case_sensitive?

activerecord/test/cases/adapters/mysql2/unsigned_type_test.rb

@@ -48,6 +48,7 @@ class UnsignedType < ActiveRecord::Base
       t.unsigned_bigint  :unsigned_bigint_t
       t.unsigned_float   :unsigned_float_t
       t.unsigned_decimal :unsigned_decimal_t, precision: 10, scale: 2
+      t.column :unsigned_zerofill, "int unsigned zerofill"
     end
 
     @connection.columns("unsigned_types").select { |c| /^unsigned_/.match?(c.name) }.each do |column|