oem: Preseed mirror again, but actually enable it

config/includes.chroot.oem/var/lib/pureos-oem/di-preseed.cfg

@@ -14,10 +14,14 @@ d-i apt-setup/cdrom/set-first boolean true
 d-i apt-setup/cdrom/set-double boolean false
 d-i apt-setup/cdrom/set-next boolean false
 d-i apt-setup/cdrom/set-failed boolean false
-d-i apt-setup/use_mirror boolean false
+d-i apt-setup/use_mirror boolean true
+
+d-i mirror/country string manual
 
 d-i  netcfg/get_hostname string librem
 d-i netcfg/get_hostname seen false
+d-i mirror/http/hostname string repo.puri.sm
+d-i mirror/http/directory string /pureos
 d-i pkgsel/install-language-support boolean false
 d-i pkgsel/update-policy select none