Description of problem:

In PF5 Settings, tab Tasks, field Task troubleshooting URL, the description says:

 Url
 pointing to the task troubleshooting documentation. It should contain 
%{label} placeholder, that will be replaced with normalized task label 
(restricted to only alphanumeric characters)). %{version} placeholder is
 also available.

It allows me to change the value to something that is not URL, like "xx".

Then, when I try to set something correct, like

https://access.redhat.com/solutions/satellite6-tasks#%{label} 

, which is the default value, it doesn't let me, showing the following:

Error updating setting: undefined

But no traceback.

When I attempt to set it to

https://access.redhat.com/solutions/satellite6-tasks#

, it passes so it doesn't like the "%{label}" part.

How reproducible:

Deterministic

Is this issue a regression from an earlier version:

Yes

Steps to Reproduce:

1. Have a Satellite with new PF5 Settings

2. Got to Administer -> Settings -> tab Tasks

3. Set "Tasks troubleshooting URL" = "xx", confirm

4. Set "Tasks troubleshooting URL" to "https://access.redhat.com/solutions/satellite6-tasks#%{label}", confirm

5. Set "Tasks troubleshooting URL" to "https://access.redhat.com/solutions/satellite6-tasks#", confirm

Actual behavior:
3 success, 4 error, 5 success

Expected behavior:
3 error, 4 success, 5 probably error because the description says "It should contain %{label} placeholder"