Because handling blockers when using the fetch function is a non sense. With the -f without --nodeps portage bailout if any blockers exist instead of doing downloading the sources
The point of -f is, that it's possible to download all required sources first and then install the packages. This would no longer work with --nodeps as the dependencies are ignored. (In reply to comment #0) > Because handling blockers when using the fetch function is a non sense. The opposite is true, because solving the blockers might change the required packages. This means that you might end up without all required sources, even if this is what -f should have done. > With the -f without --nodeps portage bailout if any blockers exist instead > of doing downloading the sources
Closing per few's comment.
