allow cases where user is not set in globals

Such cases include CLI scripts and tests. This will most likely just
delay failure, but at least it means some permissions are checked for
cases where we don't have a user.

ckanext/authz_service/authz_binding/common.py

@@ -38,15 +38,17 @@ def ckan_get_user_role_in_group(group_id):
     # tyope: (str) -> Optional[str]
     """Get the current user's role in a group / organization
     """
-    user = get_user_context()['user']
+    user = get_user_context().get('user')
+    if not user:
+        return None
     return users_role_for_group_or_org(group_id, user)
 
 
 def ckan_is_sysadmin():
     # type: () -> bool
     """Tell if the current user is a CKAN sysadmin
     """
-    user = get_user_context()['user']
+    user = get_user_context().get('user')
     return is_sysadmin(user)
 
 
@@ -59,4 +61,9 @@ def get_user_context():
     call this. This allows tests to patch this function to set the current
     user.
     """
-    return dict(model=model, user=g.user, auth_user_obj=g.userobj)
+    context = dict(model=model)
+    if hasattr(g, 'user'):
+        context['user'] = g.user
+    if hasattr(g, 'userobj'):
+        context['auth_user_obj'] = g.userobj
+    return context