Fixes QS not being added to the redirect URL

[slykar]

All Submissions:

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• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

On my WP installation the QS is lost when saving the redirect URL. Those changes fix the issue.

How to test the changes in this Pull Request:

1. go to any login-protected URL with any query string
2. login
3. you should get back to page with query string present

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?

Changelog entry

Fixes QS not being added to the redirect URL