Created by: pvdlg
This has been introduced in https://github.com/twbs/bootstrap/commit/a9bee8b6c8c31455dfba029434fad88b862c3846
Reboot set the focused color for a elements.
The button-variant mixin has to set the proper variant color in order for link button to display properly when focused.
Before:
After:
Fixes #21625 (closed).