initdb auth method option and "ident sameuser"

I recently got a complaint from an OpenSuSE user, which had problems using 
PostgreSQL 8.4 installed by a broken RPM from build service. The init 
script used initdb --auth="ident sameuser" accidentally, to initialize the 
cluster (this seems to be the practice in older versions before, too). This 
caused the whole postgres startup to fail, since 8.4 refuses to accept such 
a line anymore.

Beside the fact that this is primarily the packagers fault, I wonder wether 
we should install an additional check in initdb.c against the requested 
authmethod to check against such a usage. It seems too easy to break an 
installation with a formerly common usage practice.
       Bernd