When emerging, I get the following warning:
disabling confcache, binary cannot be found
This leads me to believe that there is a confcache. Apparently, there was, but it has been removed for what sounds like good reason. So my suggestion here is to remove the confcache option from FEATURES so that the message would be "confcache no longer supported, please remove from make.conf" or something similar.
Steps to Reproduce:
1. Add confcache to FEATURES
2. Emerge something
In svn r11770 I've removed the confache support so you won't get any warning message at all now.
This is fixed in 2.2_rc13.