Prior to this change, given tat a unix domain socket string was passed
ad `frappe.conf.redis_queue`, then the url split would have failed.
With this change, the upstream API for `from_url` is invoked
transparently.
passing none values for username and password is inocuous; [proof](d95d8a24ed/redis/connection.py (L604)) and
[proof](d95d8a24ed/redis/connection.py (L594))
The [entrypoint](d95d8a24ed/redis/client.py (L868)) passes these parameters on transparently.
