mkosi: Override /sbin/init in minimal-base

Required for TEST-13-NSPAWN.

diff --git a/mkosi.images/minimal-base/mkosi.postinst b/mkosi.images/minimal-base/mkosi.postinst
new file mode 100755 (executable)
index 0000000..c76fb0a
--- /dev/null
+++ b/mkosi.images/minimal-base/mkosi.postinst
@@ -0,0 +1,11 @@
+#!/bin/bash
+set -e
+
+# We don't use mkosi.extra because /usr/sbin could be a symlink and cp doesn't handle that properly until
+# coreutils 9.5 or newer.
+cat >"$BUILDROOT/sbin/init" <<EOF
+#!/bin/bash
+echo "Hello from dummy init, beautiful day, innit?"
+ip link
+EOF
+chmod +x "$BUILDROOT/sbin/init"