Comment # 55 on bug 968405 from Dominique Leuenberger

(In reply to Egbert Eich from comment #53)

> > But as /etc/sysconfig/service is not yet sourced at that moment, ANY package
> > not specifying it =no will NOT restart now (their value of
> > DISABLE+RESTART_ON_UPDATE is "", not 'no'
> 
> Exactly. I did propose a patch in comment #33 which sources
> /etc/sysconfig/service but so far this has been ignored completely.

Maybe I should have given more context... the sourcing of
/etc/sysconfig/services would happen right after.. so the approach is equal to
what you proposed in comment 33... first check the 'env', then source and
recheck the env variable (now coming from the file).

The difference being:
comment ee checked if DISABLE_RESTART_ON_UPDATE=yes && exit 0
and Werner's new solution doing DISABLE_RESTART_ON_UPDATE != no, which sounds
very appealing at first, but fails, as outlined above, as unless specified by
the package/user/anything else, the variable is not set at all.