reload I18n as we are defining `:ts` locale
fix build- see https://travis-ci.org/rails/rails/jobs/27578159#L2913.
Merge pull request #15737 from kuldeepaggarwal/fix-build

reload I18n as we are defining `:ts` locale  in  `test_number_to_human_with_custom_translation_scope`
[ci skip] correct doc for `register_preview_interceptor`
remove unnecessary calling of `I18n.backend.store_translations(empty, {})`

Clean up I18n stored translations after test
continuation with #15714
Merge pull request #15738 from kuldeepaggarwal/remove-unwanted-code

remove unnecessary calling of `I18n.backend.store_translations('empty', {})`
Merge pull request #15739 from y-yagi/correct_doc_for_action_mailer_base

[ci skip] correct doc for `register_preview_interceptor`