Post Repository does not respect language fallbacks

[MK-42]

Bug Report

Prerequisites

• Can you reproduce the problem on TYPO3 v8.7 LTS
• Can you reproduce the problem on TYPO3 v9.5 LTS
• Did you perform a cursory search to see if your bug or feature is already reported?

Description

In a multi-language environment the Metadata and Author Plugins won't fetch the right page-record when language fallbacks are in place and the requested page is not translated.

Steps to Reproduce

1. Create a two site languages, one (EN_gb) falling back on the other (EN_us)
2. Create a blog post in EN_us language
3. view the metadata plugin on that page in EN_gb language. Note that all output is empty, as the fallback is not used when resolving the record

Expected behavior:
the metadata plugin should show the record fields of EN_us as the language fallback is configured like that.

Actual behavior:
No content is shown, as the EN_gb language is explicitly resolved and non-existent.

Versions

9.1.2

We have a patch for the overlay in place - which I can prepare as an PR if desired