Comment # 60 on bug 1036463 from Martin Wilck

After some digging in the systemd changelog, I eventually found bug 761109,
comment 9. It turns out that until v174 (pre-systemd), udev used to have a rule
quite like the one I suggested in comment 57. This rule is still present in
SLE11-SP4 (udev 147). That rule was removed in v174 (09637f74) with the
informative log message "rules: do not load sg module". For bug 761109, Lee had
contacted the udev developers about it, and they said that loading sg from an
udev rule was "overkill" (the reason is likely to be the same that I described
in comment 59). That's how /usr/lib/modules-load.d/sg.conf came to be. 

Thus I'll revert the addition of the udev rule, and fall back to the sg.conf
approach (option 1 from comment 59). The only change will be that sg.conf is
now maintained in suse-module-tools rather than in the systemd package.

It's pretty disappointing for myself to reach this conclusion after so many
hours of digging around, but it's probably better to follow the upstream
approach.