1.6.15: Revert "Remove an old hack for migration path on references" (#4238)
This reverts commit 21e94d28be2cc65cc23110328e82b115820cb2d1. The hack is still needed, as some Cozy instances have references in the bogus format in production.
This reverts commit 21e94d28be2cc65cc23110328e82b115820cb2d1. The hack is still needed, as some Cozy instances have references in the bogus format in production.