|I ran into this too, /mnt/etc/resolv.conf is a symlink pointing at nothing at this time.
What I did:
ls -l /mnt/etc/resolv.conf # write down to restore later
cp /etc/resolv.conf /mnt/etc/resolv.conf
Then do what you want to do &
Restore that sysmlink after booting
Probably not the most elegant way but did the job for me.