New review comment by heliocat on void-packages repository

https://github.com/void-linux/void-packages/pull/29304#discussion_r589268771

Comment:
This will error for most installs that didn't come from the live image. Something like `[ -f /usr/share/xbps.d/void-virtualpackages.conf ] && sed ...` would do it. 

EDIT: I think this only fires on first install so it won't error for people coming from the live image but it probably still should be protected for other install paths. Not 100% on that though.