Mm... ok there are over 50 packages using %{_isa} in buildrequires so removing from rpm.spec alone wont do any good.
Again, a possible workaround for the %{_isa} case is to have mock generate the src.rpm with --define "_isa %{nil}" but there's no generic way to eliminate arch-dependent pieces ending up in src.rpms. Of course this way its possible to have build-requires depsolve succeed but actual build still fail due to missing buildrequires. Which is probably better than not being able to depsolve them at all, but somewhat ugly.
Mm... ok there are over 50 packages using %{_isa} in buildrequires so removing from rpm.spec alone wont do any good.
Again, a possible workaround for the %{_isa} case is to have mock generate the src.rpm with --define "_isa %{nil}" but there's no generic way to eliminate arch-dependent pieces ending up in src.rpms. Of course this way its possible to have build-requires depsolve succeed but actual build still fail due to missing buildrequires. Which is probably better than not being able to depsolve them at all, but somewhat ugly.