Revert "Merge pull request #43604 from nikonoid/bug/31722"

This reverts commit 2374f0efed, reversing
changes made to b37c02e027.

Since this break existing applications, and is necesary only because
applications are not using timestamped migrations and are expecting it
to just work, I decided to not revert this.

Those application should either follow the timestamped migrations format
or disable it.

activerecord/lib/active_record/migration.rb

@@ -1001,7 +1001,7 @@ module ActiveRecord
     # Determines the version number of the next migration.
     def next_migration_number(number)
       if ActiveRecord.timestamped_migrations
-        [Time.now.utc.strftime("%Y%m%d%H%M%S").to_i, ("%.14d" % number).to_i].max
+        [Time.now.utc.strftime("%Y%m%d%H%M%S"), "%.14d" % number].max
       else
         SchemaMigration.normalize_migration_number(number)
       end

activerecord/test/cases/migration_test.rb

@@ -148,15 +148,6 @@ class MigrationTest < ActiveRecord::TestCase
     assert_equal 20131219224947, migrator.current_version
   end
 
-  def test_migration_next_migration_number_consistent_across_year_boundary
-    last_year = Time.now.year - 1
-    not_a_month = 14
-    day_of_month = Time.now.day
-    time = Time.now.utc.strftime("%H%M%S")
-    last_year_number = "#{last_year}#{not_a_month}#{day_of_month}#{time}01"
-    assert_equal last_year_number, ActiveRecord::Migration.new.next_migration_number(last_year_number).to_s
-  end
-
   def test_create_table_raises_if_already_exists
     connection = Person.connection
     connection.create_table :testings, force: true do |t|