Nothing obvious changed in either dracut or busybox, but now rebuilding
drakx-installer-images with debug enabled results in a hang install stage1 startup:
"can't run '/etc/init.d/rcS': No such file or directory
can't open /dev/tty4: No such file or directory"

The regular stage1 contains a dracut script as /init.
Whereas using dracut busybox module results in /init being a softlink to
busybox which then fails to start the installer:

$ ls -l {KO,OK}/init
lrwxrwxrwx 1 tv   users      15 Eos  12 21:58 KO/init -> usr/bin/busybox*
-rwxr-xr-x 1 tv   users   12033 Eos  12 22:00 OK/init*

An alternative would be to alter the 90mgainstaller dracut module so that it
owerwrites init again with /usr/lib/dracut/modules.d/99base/init.sh.
Which is not better.

--- ./modules.d/05busybox/module-setup.sh	2020-08-12 22:13:36.027879626 +0200
+++ ./modules.d/05busybox/module-setup.sh	2020-08-12 22:13:29.365724091 +0200
@@ -20,6 +20,7 @@ install() {
     inst "$_busybox" /usr/bin/busybox
     for _i in $($_busybox --list); do
         [[ ${_i} == busybox ]] && continue
+        [[ ${_i} == init ]] && continue
         _progs+=("${_i}")
     done