Project import on GitLab.com does not work

I briefly turned 'GitLab export' import source on for GitLab.com. I tried to import a test project of mine and it failed with a file/directory permission error. The path in shared/tmp/project_exports was either not there or couldn't be read. I'm not sure if this is a bug in Omnibus or just an Infra issue.

@jameslopez You may have some ideas here.

The feature is off for now since it's not working.