os-prober is a very expensive operation. During a fresh install nothing sets
GRUB_DISABLE_OS_PROBER and as a result whatever pkg thinks it needs to create a
grub.cfg will stall the install. 7 minutes in my case.

30-os_prober has just a single check for GRUB_DISABLE_OS_PROBER, and it checks
only if its value is "true". Since per default the value is not set every fresh
install will waste its time trying to find other installations on the attached
disks.

At the very end of the installation, after all pkgs are installed and after all
posttrans scripts are called, yast will set GRUB_DISABLE_OS_PROBER= to the
specified value and creates grub.cfg once more.

In my case 3*7 minutes are wasted just in the os-prober calls.

the correct thing to do is:

--- /etc/grub.d/30_os-prober    2016-08-27 00:26:49.000000000 +0200
+++ 30_os-prober        2016-09-06 11:08:19.228331112 +0200
@@ -26,7 +26,7 @@ export TEXTDOMAINDIR="${datarootdir}/loc

 . "$pkgdatadir/grub-mkconfig_lib"

-if [ "x${GRUB_DISABLE_OS_PROBER}" = "xtrue" ]; then
+if [ "${GRUB_DISABLE_OS_PROBER}" != "false" ]; then
   exit 0
 fi