Database error: `ActiveRecord::StatementInvalid: PG::CheckViolation: ERROR: check constraint "check_0dd5948e38" of relation "users" is violated by some row`

Summary

Error:

Restoring a backup
Uploaded 15.10.0_gitlab_backup.tar
Scaling Deployment ('app=webservice,release=<release>') to 0.
Scaling Deployment ('app=sidekiq,release=<release>') to 0.
WARNING: Migrations did not succeed:
...
ActiveRecord::StatementInvalid: PG::CheckViolation: ERROR: check constraint "check_0dd5948e38" of relation "users" is violated by some row
...

Context:

• !3212 (comment 1446339590)
• #4835 (comment 1446348968)

This happened even after a database reset (scale down PG, delete PG PVC, scale PG back up, run migrations from Toolbox).

Occurs during review_specs_<environment> jobs in CI.