Since when is listing all the directories in an install mandatory?

[Christian Goetze <cg sensage com>]

Recently, I've been observing RPM installs to fail because it tries to 
copy I file into a non-existing directory. I also observed that rpmbuild 
will now warn me with "directories not explicitly listed".

My understanding was that a directory listed with %dir was for exclusive 
use by that rpm. I'm probably wrong there, but I'm still annoyed that I 
now have to go through all the spec files and add the %dir entries in 
the %files list.
--
cg