fix /media/filesystem mount

live-build/ubuntu-server/includes.chroot.ubuntu-server-minimal.ubuntu-server.installer/usr/lib/systemd/system/media-filesystem.mount

@@ -1,5 +1,9 @@
+[Unit]
+Requires=media-full.mount media-minimal.mount
+After=media-full.mount media-minimal.mount
+
 [Mount]
 What=/cdrom/casper/ubuntu-server-minimal.ubuntu-server.squashfs
 Where=/media/filesystem
-Type=squashfs
-Options=ro
+Type=overlay
+Options=ro,lowerdir=/media/full:/media/minimal

live-build/ubuntu-server/includes.chroot.ubuntu-server-minimal.ubuntu-server.installer/usr/lib/systemd/system/media-full.mount

@@ -0,0 +1,5 @@
+[Mount]
+What=/cdrom/casper/ubuntu-server-minimal.ubuntu-server.squashfs
+Where=/media/full
+Type=squashfs
+Options=ro

live-build/ubuntu-server/includes.chroot.ubuntu-server-minimal.ubuntu-server.installer/usr/lib/systemd/system/media-minimal.mount

@@ -0,0 +1,5 @@
+[Mount]
+What=/cdrom/casper/ubuntu-server-minimal.squashfs
+Where=/media/minimal
+Type=squashfs
+Options=ro