Description of problem:
Issue is specific to API part only. When I try to update repository label value - no error shown and nothing happened with entity

Making HTTP POST request to https://server.com/katello/api/v2/repositories with options {'verify': False, 'auth': ('login', 'pass'), 'headers': {'content-type': 'application/json'}} and data {"product_id": 149, "content_type": "yum", "url": "url", "name": "test_name"}.

Received HTTP 200 response: {...,"id":72,"name":"test_name","label":"df0d496f-c7f9-4ba0-b3ad-8cb98bc76609","content_type":"yum",...}

Making HTTP PUT request to https://server/katello/api/v2/repositories/72 with options {'verify': False, 'auth': ('login', 'pass'), 'headers': {'content-type': 'application/json'}} and data {"label": "ZQmZIjTjpX"}.

Received HTTP 200 response: {...,"id":72,"name":"name","label":"df0d496f-c7f9-4ba0-b3ad-8cb98bc76609","content_type":"yum",...}

For example for product we will get next error in the same situation:
"Validation failed: Label cannot be changed."

Version-Release number of selected component (if applicable):
6.1.7

How reproducible:
Always

Steps to Reproduce:
1. Attempt to change repository label
2.
3.

Actual results:
No error shown. No changes to entity happened

Expected results:
"Validation failed: Label cannot be changed." error should be raised

Additional info: