Try harder in skipping the MSFT compat rules

The by-id/ MS compatibility hack links that were added
as a maintenance update (and thereby are available in
the discovery image) are not recognized by the SP3 install
media, hence missing during install, which breaks.

The previous regexp was not good enough, some harddrives
do not start their naming with a letter, but a number. In
this case it seems udev always prefixes it with "2", so
hopefully this regexp is good enough..

https://bugzilla.novell.com/show_bug.cgi?id=864857
(cherry picked from commit 3a3238fc0d1d578ff02ba5a2dac8d0d5b99bffea)
Merge pull request #274 from dirkmueller/bootdisk_fixup

Try harder in skipping the MSFT compat rules