Rebuilding RPMs results in bad update behavior

[J French]

If I have a fully updated system and I decide I want to oh, say rebuild 
the nautilus rpm on my system to make it faster, I go download the 
latest version src.rpm (which happens to be the same version I have 
installed) and rebuild it on my system.

This is the way you should be doing things on a server, by the way - at 
least for those packages you want optimized. I don't do automatic 
updates on my servers though, so never noticed this before.

Now, when I go to rpm -Uvh the resulting rpm, I get "the installed 
version is NEWER than this one". How in the world is this even possible? 
So now, any packages I rebuild get marked as older than the binaries? 
Are we building our RPMs in the future now? What's determining the age 
of these RPMs - it's certainly not the build time. What's determining 
whether or not a package should be updated - it's certainly not the 
version number.

In short, do I have to actually unpack any rpms I want to rebuild and go 
change the version number in the source to stop this from happening?

Oh yes, one last thing: On my dual Opteron 246 running in 32-bit mode (I 
use 32-bit for my desktop for compatability reasons), rebuilding 
Metacity and Nautilus make the desktop *very* much more responsive than 
the binary packages. No surprise there, the only real surprise was when 
I logged into my newly lightning fast desktop and was informed that 
there were updates to these packages (of the same version number).

I'm guessing this is a bug in either rpm or rpmbuild, but I'd like more 
input before I file one.