$ ROOT="/home/nirbheek/build-area/beagle-test/" pmerge app-misc/beagle[doc]
Error in configuration:
Instantiating default domain 'livefs domain':
Caught exception "initialization failed: lstat failed on base '/home/nirbheek/build-area/beagle-test/var/db/pkg'" instantiating pkgcore.vdb.ondisk.tree