Some Container Repository syncs fail

https://gitlab.zendesk.com/agent/tickets/143263

I have setup geo replication to a single secondary node. Recently we added container registry replication as well. This has worked for the first 75% of repositories but seems stuck on the last 25%.

{"severity":"ERROR","time":"2020-01-07T22:31:19.934Z","correlation_id":"a25def8f-9e21-482f-88ae-cc47d356af74","class":"Geo::ContainerRepositorySyncService","project_id":6153,"project_path":"Alis**/DockerCasin**","container_repository_name":"","message":"Container repository sync failed","job_id":"a129cc30ed409b309938cfe9","error":"undefined method `[]' for nil:NilClass"}

{"severity":"ERROR","time":"2020-01-08T01:39:14.781Z","correlation_id":"d98455b8-4065-4f47-bc10-8ddd444563f6","class":"Geo::ContainerRepositorySyncService","project_id":8082,"project_path":"dcr/selenium","container_repository_name":"","message":"Container repository sync failed","job_id":"14f758d4dd69a68cf8925b23","error":"Push Blob error: {\"errors\"=\u003e[{\"code\"=\u003e\"DIGEST_INVALID\", \"message\"=\u003e\"provided digest did not match uploaded content\", \"detail\"=\u003e{\"Digest\"=\u003e\"sha256:3889bb8d808bbae6fa5a33e07093e65c31371bcf9e4c38c21be6b9af52ad1548\", \"Reason\"=\u003e{}}}]}"}