With devfs you should not have /dev/pts mounted ... check that this is not mounted and please try again .. feedback will be appreciated.
Confirmed I am having this problem on one of my machines I just installed gentoo on.
Fixed in CVS Portage and in baselayout-1.7.1-r1. This will continue to bite people until these older merged ebuilds get phased out.
*** Bug 1384 has been marked as a duplicate of this bug. ***