Create button is disabled in Git Import form when git repo url has hyphens in owner part of the url

Description of problem:

When adding a repository url that contains hyphens in the <owner> part of the url
(<https://github.com/owner/url> - eg https://github.com/redhat-developer/s2i-dotnetcore-ex.git), then create button stays disabled and validation errors are not presented in the UI.

Version-Release number of selected component (if applicable):
4.9

How reproducible:
Always

Steps to Reproduce:
1. Go to Developer -> Add -> Import from Git page
2. use the repo url https://github.com/redhat-developer/s2i-dotnetcore-ex.git
3. add `/app` in the context dir under advanced git options.

Actual results:

1Once the builder image is detected, then Create button is disabled but no errors in the form. When the user touches the name field and then name validation error message is shown even if the suggested name is valid.

Expected results:

After detecting the builder image, the create button should be enabled.

Additional info: