Horizon Internal Server Error navigating to the Images page on system configured with https

[Wendy Mitchell]

Brief Description
-----------------
STX Horizon: Internal Server Error navigating to the Images page in Horizon on system configured with https

Severity
--------
Standard

Steps to Reproduce
------------------
1. Log into Horizon
2. Navigate to Compute - Images

Expected Behavior
------------------
Expect Images page to display (list images)

Actual Behavior
----------------
[ERROR] django.request: Internal Server Error: /admin/images/
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/django/core/handlers/base.py", line 132, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/lib/python2.7/site-packages/horizon/decorators.py", line 52, in dec
    return view_func(request, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/horizon/decorators.py", line 36, in dec
    return view_func(request, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/horizon/decorators.py", line 84, in dec
    return view_func(request, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/horizon/decorators.py", line 52, in dec
    return view_func(request, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/horizon/decorators.py", line 36, in dec
    return view_func(request, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/horizon/decorators.py", line 84, in dec
    return view_func(request, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/django/views/generic/base.py", line 71, in view
    return self.dispatch(request, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/django/views/generic/base.py", line 89, in dispatch
    return handler(request, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/horizon/tables/views.py", line 228, in get
    handled = self.construct_tables()
  File "/usr/lib/python2.7/site-packages/horizon/tables/views.py", line 211, in construct_tables
    tables = self.get_tables().values()
  File "/usr/lib/python2.7/site-packages/horizon/tables/views.py", line 268, in get_tables
    self._tables[self.table_class._meta.name] = self.get_table()
  File "/usr/lib/python2.7/site-packages/horizon/tables/views.py", line 279, in get_table
    self.table = self.table_class(self.request, **self.kwargs)
  File "/usr/share/openstack-dashboard/openstack_dashboard/dashboards/project/images/images/tables.py", line 392, in __init__
    not base.is_stx_region(request):
  File "/usr/share/openstack-dashboard/openstack_dashboard/api/base.py", line 391, in is_stx_region
    if not base.is_service_enabled(request, 'platform'):
NameError: global name 'base' is not defined

Reproducibility
---------------
Reproducible

System Configuration
--------------------
https system

Branch/Pull Time/Commit
-----------------------

Timestamp/Logs
--------------

[Ghada Khalil (gkhalil)]

Targeting stx.2018.10 as this issue impacts the usability of horizon on systems configured with https which is a common deployment as it is more secure.

[Tyler Smith (tyler.smith)]

I've verified that this issue has been resolved by this change to stx-horizon: https://github.com/starlingx-staging/stx-horizon/pull/8