Misconfigured connection to s3 can cause hangs

[bio-boris]

A correct workspace server startup ends with

[1] [-] [-] [-] [-] [-]: Temporary file location: ws_temp_dir

[1] [-] [-] [-] [-] [-]: Initialized S3 backend

 [-] [-] [-] [-] [-]: Started workspace server instance 1. Free mem: 2450303608 Total mem: 2550136832, Max mem: 32178700288

However, it can get stuck and not progress past

[1] [-] [-] [-] [-] [-]: Temporary file location: ws_temp_dir

The server hangs while attempting to establish a connection to s3. I'm not sure if its through the object store or through its direct connection to s3. Adding debugging statements in #747 helped me figure out that this is issue

This issue might be caused by a combination of

• incorrect s3 url configuration
• incorrect permissions on the credentials used (e.g. no proper ACLs added to the specific users)