on Web GUI gives error: "Oops, we're sorry but something went wrong Validation failed: Taxonomy has already been taken"

Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1786415

Description of problem: Changing the location of hosts to 'Default Location' on Satellite GUI gives error: "Oops, we're sorry but something went wrong Validation failed: Taxonomy has already been taken"

Version-Release number of selected component (if applicable): 6.6.1

How reproducible: Everytime

Steps to Reproduce:
1. Change the location of a host which is in Default location to any other location.
--> On Satellite GUI --> Hosts --> All Hosts --> Assign location --> select location from Drop-Down list --> tick-mark 'Fix Location on Mismatch' --> Submit

2. Now try to change the location of the same host to Default Location will result in error "Oops, we're sorry but something went wrong Validation failed: Taxonomy has already been taken".

3. Inspite of the error observed the location is getting updated for the host.
Confirmed through: # hammer host info --id=host_id

Actual results: Error is observed and action is still performed

Expected results: Error should not be displayed and the action should be performed.

Additional info: Tried updating the location using hammer as well but observed that it was giving following error:
_~~

1. hammer host update --location-id=3 --id=154 --organization-id=1
   Could not update the host:
   Resource host not found by id '154'
   ~~~

Seems that this is a regression of bug # 1679300