Currently on multilib systems anaconda writes a %_transaction_color entry into the unowned /etc/rpm/macros file. It looks like rpm for some ppc64/ia64a archs wasn't defaulting to 3, for x86_64 I checked that for all multilib releases (RHEL3/4 and FC2-6) the setting %_transaction_color to 3, so it's doing the right thing w/o any entry in /etc/rpm/macros. If this has been fixed in ppc64's rpm could this entry be left off? Ideally /etc/rpm/macros should be used only by users to modify rpm behaviour, it can happen (there are a couple of bug reports in here), that this entry gets nuked, especially since this currently /etc/rpm/macros is unowned (see also bug #204606). Also if this entry is important many buildroot constructing systems are missing this, so it should move from anaconda to rpm. I suggest to o either not set anything in /etc/rpm/macros if it is indeed redundand by now, o or, if it is needed in some scenarios to place it into some other /etc/rpm/macros.* file and make that owned by some prominent package like rpm itself.
Unfortunately, this can't be not written out as on ppc you definitely don't get the right thing (since you're running a ppc32 rpm instead of ppc64, chaos then ensues). There's a really old bug against rpm about this. We could change it to /etc/rpm/macros.somethingelse, though I guess
We also need to set color preference now for ppc64 so we need to write out the macros file