localhost ~ # emerge sabayon-sources
Calculating dependencies \!!! A file listed in the Manifest could not be found: /usr/portage/local/layman/sabayon/sys-kernel/sabayon-sources/sabayon-sources-2.6.20_rc7.ebuild

!!! All ebuilds that could satisfy "sys-kernel/sabayon-sources" have been masked.
!!! One of the following masked packages is required to complete your request:
- sys-kernel/sabayon-sources-2.6.23-r1 (masked by: corruption)

For more information, see MASKED PACKAGES section in the emerge man page or
refer to the Gentoo Handbook.