Description of problem: ipa-advise without any advise displays 'object of type
'type' has no len()'

Version-Release number of selected component (if applicable):
ipa-server-4.4.0-1.el7.x86_64

How reproducible:Always


Steps to Reproduce:
1. Install ipa-server
2. run ipa-advise command

Actual results:
[root@server ~]# ipa-advise
----------------------------------------------------------------------
List of available advices
----------------------------------------------------------------------
object of type 'type' has no len()
The ipa-advise command failed.

Expected results:
Although there are no advisories for customers right now for this release the
command should display proper message instead of displaying that the command
failed.

Additional info: