Multi-language page title in repeater don't save value when only one (default) language is exists

[esl51]

Short description of the issue

Multi-language page title in repeater don't save value when only one (default) language is exists. When adding another language - all working as expected.

Expected behavior

Multi-language page title in repeater saves value

Actual behavior

Multi-language page title in repeater don't save value

Steps to reproduce the issue

1. Activate Multi-language modules
2. Make title field multi-language
3. Create repeater field, which includes title and some other fields
4. Add new field to any template
5. Create new page with this template
6. Add repeater item and fill up title field
7. Save page
8. Check repeater item and it's title field

• ProcessWire version: 3.0.123
• (Optional) PHP version: 7.0.33
• (Optional) MySQL version: MariaDB 10.1.38
• (Optional) Any 3rd party modules that are installed and could be related to the issue:

[noelboss]

Probably related: https://processwire.com/talk/topic/23167-ajax-repeater-wrong-language-field-active-🐞-or-just-me/?tab=comments#comment-198047