Hi Atim,
First of all: welcome!
The bu you linked (see [1]) describes an openstackclient issue for Neutron, I checked it with current master, and the error msg seems ok:
$ openstack extension list --network
Failed to retrieve extensions list from Network API
So the issue seems to be fixed, but anyway by openstack policies we first fix bugs on master and backport them to older branches.
From your comment on the bug, you are an outreachy applicant, perhaps try to ask for your mentor who can help you find things to help your learning.
Lajos Katona(lajoskatona