Description of problem:
When trying to add/edit registry input, for example in template -> edit boot source, and you try to delete the cocker prefix it add another one.

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

How reproducible:
100%

Steps to Reproduce:
1. checked attached video
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Actual results:
Adding twice docker prefix

Expected results:
Not adding twice docker prefix or just don't add docker prefix to input

Additional info: