Github Import: inconsistent import of pull request assignees/reviewers

When importing github repo with pull request that has reviewer assigned, behaviour is not consistent if user is not mapped in gitlab instance. I couldn't find description of what is the expected behaviour when user is not matched in the docs, only that reviewer would be migrated when it is matched.

• Imported mr has event stating that user doing the import was assigned as reviewer
• Event stating that same user is set as assignee is also created
• Comment that mr was approved by original user on the github side is created

However, despite the events, non of the actions actually happen for the mr itself

• mr has no assignees
• mr has no reviewers
• mr doesn't have approval

events:

mr:

approvals:

Reproducible by importing repo: https://github.com/gitlab-qa-github/import-test