Thank you for the fast reply.
Having those external repositories should be a problem because:
1)
epel, uses the repo
"https://rpm.nodesource.com/pub_8.x/el/$releasever/$basearch" and the other ones
will fail.
works as expected
2)
fedora-27-i386 --> has a nodejs repo, still fails and disables it. It should have used
"https://rpm.nodesource.com/pub_8.x/fc/$releasever/$basearch" repo
does not work as expected. this is the particular case where the repo should have been
downloaded but fails like it was offline
3)
fedora-28 and rawhide --> does not have a repo, but hits on the fc/27/ repo
I can, indeed, configure repo for fedora epel 7 and fedora 26 and use fedora own's
version of npm/nodejs for fedora 27 up to rawhide.
Nevertheless, I'm taking your suggestion and have two rpm specs for different
chroots.
Thank you.