New issue by paper42 on void-packages repository

https://github.com/void-linux/void-packages/issues/38091

Description:
The first 3 packages were updated/revbumped in srcpkgs, but `xorg-server` is the first package that's outdated on the host system, but the new version is already committed to master of void-packages and the package is built. Currently the builds stop there, so `nautilus` and other packages are not built.

Without `-E`, xbps-src would just build all packages again including `xorg-server` and continue with the builds.

With `-E` I would expect it to skip already built packages (the first 3) and build `xorg-server` because it's not in the local repository.
```
./xbps-src update-sys -E
=> xbps-src: the following packages must be rebuilt and updated:
 gnome-desktop
 libadwaita
 gnome-settings-daemon
 xorg-server
 nautilus
 gnome-control-center
 mutter
 cheese
 evince
 xdg-desktop-portal-gnome
 wireplumber
 totem
 gnome-shell
 gnome-session
 gnome-initial-setup
 gnome-clocks
 gnome-books
 file-roller
 eog
 ImageMagick
=> xbps-src: building gnome-desktop-43.alpha_1 ...
=> xbps-src: gnome-desktop-43.alpha_1: found (x86_64) (/host/binpkgs/gnome43)
=> xbps-src: building libadwaita-1.2.alpha_1 ...
=> xbps-src: libadwaita-1.2.alpha_1: found (x86_64) (/host/binpkgs/gnome43)
=> xbps-src: building gnome-settings-daemon-42.2_2 ...
=> xbps-src: gnome-settings-daemon-42.2_2: found (x86_64) (/host/binpkgs/gnome43)
=> xbps-src: xorg-server-21.1.4_1: found (x86_64) (https://repo-default.voidlinux.org/current)
```