Description of problem:
"Failed to synchronize cache for repo 'rhel-8-for-x86_64-appstream-beta-rpms', ignoring this repo " on system registered and auto-attached using the environment values set for the proxysin

Version-Release number of selected component (if applicable):
[root@ibm-x3650m4-01-vm-05 ~]# subscription-manager version
server type: Red Hat Subscription Management
subscription management server: 2.3.12-1
subscription management rules: 5.30.1
subscription-manager: 1.23.8-18.el8

How reproducible:

Steps to Reproduce:
[root@ibm-x3650m4-01-vm-05 ~]# export https_proxy=https://redhat:redhat@auto-services.usersys.redhat.com:3127
[root@ibm-x3650m4-01-vm-05 ~]# echo $https_proxy
https://redhat:redhat@auto-services.usersys.redhat.com:3127
[root@ibm-x3650m4-01-vm-05 ~]# subscription-manager register --force --auto-attach
Registering to: subscription.rhsm.stage.redhat.com:443/subscription
Username: shwetha_tier1_test
Password:
The system has been registered with ID: 2808a738-7437-4cb3-b19e-0a941456d30f
The registered system name is: ibm-x3650m4-01-vm-05.lab.eng.bos.redhat.com
Installed Product Current Status:
Product Name: Red Hat Enterprise Linux for x86_64 High Touch Beta
Status: Subscribed

[root@ibm-x3650m4-01-vm-05 ~]# dnf repolist
Updating Subscription Management repositories.
Red Hat Enterprise Linux 8 for x86_64 - AppStream HTB (RPMs) 0.0 B/s | 0 B 00:00
Red Hat Enterprise Linux 8 for x86_64 - BaseOS HTB (RPMs) 0.0 B/s | 0 B 00:00
Failed to synchronize cache for repo 'rhel-8-for-x86_64-appstream-htb-rpms', ignoring this repo.
Failed to synchronize cache for repo 'rhel-8-for-x86_64-baseos-htb-rpms', ignoring this repo.

[root@ibm-x3650m4-01-vm-05 ~]# tail -f /var/log/rhsm/rhsm.log | grep proxy
2019-02-06 10:17:09,773 [INFO] dnf:31564:MainThread @connection.py:924 - Connection built: http_proxy=auto-services.usersys.redhat.com:3127 host=subscription.rhsm.stage.redhat.com port=443 handler=/subscription auth=identity_cert ca_dir=/etc/rhsm/ca/ insecure=False
2019-02-06 10:17:09,852 [INFO] dnf:31564:MainThread @connection.py:924 - Connection built: http_proxy=auto-services.usersys.redhat.com:3127 host=subscription.rhsm.stage.redhat.com port=443 handler=/subscription auth=identity_cert ca_dir=/etc/rhsm/ca/ insecure=False

Actual results:
Failed to synchronize cache for repo 'rhel-8-for-x86_64-appstream-htb-rpms', ignoring this repo.
Failed to synchronize cache for repo 'rhel-8-for-x86_64-baseos-htb-rpms', ignoring this repo.

Expected results:
Updating Subscription Management repositories.
Red Hat Enterprise Linux 8 for x86_64 - AppStream HTB (RPMs) 6.8 kB/s | 4.1 kB 00:00
Red Hat Enterprise Linux 8 for x86_64 - BaseOS HTB (RPMs) 2.9 kB/s | 4.1 kB 00:01

repo id repo name status
rhel-8-for-x86_64-appstream-htb-rpms Red Hat Enterprise Linux 8 for x86_64 - AppStream HTB (RPMs) 7,789
rhel-8-for-x86_64-baseos-htb-rpms Red Hat Enterprise Linux 8 for x86_64 - BaseOS HTB (RPMs) 3,717

Additional info: