[bts]

They are, and they absolutely should be. They're completely separate projects/repositories from those from which they came. The owner of a forked repository is completely free to make whatever changes they please -- from a few bug fixes to taking projects in completely new directions (as I've done with a forked repository of my own). As far as GitHub is concerned, in the context of a forked repository being a first-class citizen, it's a minor detail that the code was originally "copied" (to use the term loosely) from somewhere else.