In TAS 2.8 & 2.9, there is an option to enable the use of 'Signed URLs' for the Director Blobstore, when using an external S3-Compatible Blobstore.
If this option is selected, but the S3 storage solution does not support signed URLs, a blank hostname will be returned to the Director and subsequent calls to the Blobstore will fail with the error:
Fetching package blob : Executing GET request: Get http:///<bucket-name>/<package-id>: http: no Host in request URL