Merge pull request #1444 from koic/fix_an_incorrect_behavior_when_using_migrated_schema_version

Fix an incorrect behavior when using `AllCops: MigratedSchemaVersion`

Author: koic

changelog/fix_an_incorrect_behavior_when_using_migrated_schema_version.md

@@ -0,0 +1 @@
+* [#1444](https://github.com/rubocop/rubocop-rails/pull/1444): Fix an incorrect behavior when using `AllCops: MigratedSchemaVersion`. ([@koic][])

config/default.yml

@@ -28,7 +28,7 @@ AllCops:
   # By specifying `MigratedSchemaVersion` option, migration files that have been migrated can be ignored.
   # When `MigratedSchemaVersion: '20241231000000'` is set. Migration files lower than or equal to '20250101000000' will be ignored.
   # For example, this is the timestamp in db/migrate/20250101000000_create_articles.rb.
-  MigratedSchemaVersion: ~
+  MigratedSchemaVersion: '19700101000000' # NOTE: Used as a sentinel value for the UNIX epoch time.
 
 Lint/NumberConversion:
   # Add Rails' duration methods to the ignore list for `Lint/NumberConversion`