I found two ways to make emerge lm_sensors loop forever while emerging sys-apps/lm_sensors-2.10.0 on amd64 on a stock 2006.1 from livecd. 1. if /usr/src/linux/include/linux/autoconf.h doesn't exist: for example, gentoo-sources is installed and there is a .config file, but make oldconfig has not been run (note: does it make sense to zcat /proc/config.gz > /usr/src/linux/.config if the first exists but not the second?) 2. if the date is set far back in the past (6 months, in my case). haven't tried to reproduce this yet, but it happened after i fixed the first problem.
#2 is not a bug, there's nothing we could do about it, you need to fix your system clock. Can't reproduce the state you are describing in #1 either, the ebuild bails out on unconfigured kernel when it runs linux-info_pkg_setup here.
Not reproducible.
