An contrived example: let's say an unfixed Bootstrap 3 bug is that there is a formatting error when rendering "div.jumbotron > h1 > span.label > small". You could replace the last small with you own css class and be done.
Contrast that to a bug in Angular, for example, that enabled a XSS bug. You'd want to upgrade Angular, instead of manually patching or adding a workaround to all your forms.
An contrived example: let's say an unfixed Bootstrap 3 bug is that there is a formatting error when rendering "div.jumbotron > h1 > span.label > small". You could replace the last small with you own css class and be done.
Contrast that to a bug in Angular, for example, that enabled a XSS bug. You'd want to upgrade Angular, instead of manually patching or adding a workaround to all your forms.
That's what I was thinking, at least.