See the copy-paste from below. The apache2_modules_access_compat is marked (+) in the dep string, because it does not exist for version 2.2, yet it's reported in the error message.. that doesn't look right. spacedock2 ~ # emerge -avuDN @world @system These are the packages that would be merged, in order: Calculating dependencies... done! [ebuild U ] sys-apps/grep-2.14 [2.12] USE="-nls -pcre" 0 kB [ebuild R ] sys-apps/busybox-1.20.2 USE="ipv6 pam static* -livecd -make-symlinks -math -mdev -savedconfig (-selinux) -sep-usr -systemd" 0 kB [ebuild N ] dev-perl/FCGI-0.740.0 0 kB [ebuild R ] net-misc/openssh-5.9_p1-r4 USE="hpn pam -X -X509 -bindist% -kerberos -ldap -libedit (-selinux) -skey -static -tcpd" 0 kB [ebuild R ] www-servers/apache-2.2.23:2 USE="ssl static suexec -debug -doc -ldap (-selinux) -threads" APACHE2_MODULES="actions alias auth_digest authn_default authn_file authz_host authz_user cgi cgid* deflate dir env expires filter headers log_config logio mime mime_magic negotiation proxy proxy_ajp proxy_http reqtimeout rewrite setenvif speling status unique_id -asis -auth_basic -authn_alias -authn_anon -authn_dbd -authn_dbm -authz_dbm -authz_default -authz_groupfile -authz_owner -autoindex -cache -cern_meta -charset_lite -dav -dav_fs -dav_lock -dbd -disk_cache -dumpio -ext_filter -file_cache -ident -imagemap -include -info -log_forensic -mem_cache -proxy_balancer -proxy_connect -proxy_ftp -proxy_scgi -substitute -userdir -usertrack -version -vhost_alias" APACHE2_MPMS="-event -itk -peruser -prefork -worker" 0 kB [ebuild U ] dev-libs/geoip-1.4.8-r1 [1.4.8] USE="ipv6 -perl-geoipupdate -static-libs" 0 kB [ebuild U ] net-dns/bind-tools-9.9.2 [9.9.1_p2] USE="idn ipv6 ssl urandom -doc -gssapi -readline -xml" 0 kB [ebuild U ~] www-misc/awstats-7.1_p20121017 [7.1-r2] USE="geoip ipv6" 0 kB [ebuild U ~] net-analyzer/munin-2.0.7-r6 [2.0.7-r5] USE="apache%* cgi* http ipv6 mysql ssl syslog -asterisk -dhcpd -doc -ipmi -irc -java -memcached -minimal -postgres {-test}" 0 kB Total: 9 packages (5 upgrades, 1 new, 3 reinstalls), Size of downloads: 0 kB The following USE changes are necessary to proceed: #required by net-analyzer/munin-2.0.7-r6[apache], required by @flameeyes-munin, required by @montgomery, required by @selected, required by @world (argument) =www-servers/apache-2.2.23 apache2_modules_cgid apache2_modules_access_compat Use --autounmask-write to write changes to config files (honoring CONFIG_PROTECT). spacedock2 ~ # emerge -avuDN @world @system These are the packages that would be merged, in order: Calculating dependencies... done! [ebuild U ] sys-apps/grep-2.14 [2.12] USE="-nls -pcre" 0 kB [ebuild R ] sys-apps/busybox-1.20.2 USE="ipv6 pam static* -livecd -make-symlinks -math -mdev -savedconfig (-selinux) -sep-usr -systemd" 0 kB [ebuild N ] dev-perl/FCGI-0.740.0 0 kB [ebuild R ] net-misc/openssh-5.9_p1-r4 USE="hpn pam -X -X509 -bindist% -kerberos -ldap -libedit (-selinux) -skey -static -tcpd" 0 kB [ebuild R ] www-servers/apache-2.2.23:2 USE="ssl static suexec -debug -doc -ldap (-selinux) -threads" APACHE2_MODULES="actions alias auth_digest authn_default authn_file authz_host authz_user cgi cgid* deflate dir env expires filter headers log_config logio mime mime_magic negotiation proxy proxy_ajp proxy_http reqtimeout rewrite setenvif speling status unique_id -asis -auth_basic -authn_alias -authn_anon -authn_dbd -authn_dbm -authz_dbm -authz_default -authz_groupfile -authz_owner -autoindex -cache -cern_meta -charset_lite -dav -dav_fs -dav_lock -dbd -disk_cache -dumpio -ext_filter -file_cache -ident -imagemap -include -info -log_forensic -mem_cache -proxy_balancer -proxy_connect -proxy_ftp -proxy_scgi -substitute -userdir -usertrack -version -vhost_alias" APACHE2_MPMS="-event -itk -peruser -prefork -worker" 0 kB [ebuild U ] dev-libs/geoip-1.4.8-r1 [1.4.8] USE="ipv6 -perl-geoipupdate -static-libs" 0 kB [ebuild U ] net-dns/bind-tools-9.9.2 [9.9.1_p2] USE="idn ipv6 ssl urandom -doc -gssapi -readline -xml" 0 kB [ebuild U ~] www-misc/awstats-7.1_p20121017 [7.1-r2] USE="geoip ipv6" 0 kB [ebuild U ~] net-analyzer/munin-2.0.7-r6 [2.0.7-r5] USE="apache%* cgi* http ipv6 mysql ssl syslog -asterisk -dhcpd -doc -ipmi -irc -java -memcached -minimal -postgres {-test}" 0 kB Total: 9 packages (5 upgrades, 1 new, 3 reinstalls), Size of downloads: 0 kB Would you like to merge these packages? [Yes/No]
We might vary the behavior depending on the --autounmask-unrestricted-atoms option, since even though the defaults of the current package make some USE settings unnecessary, there may be new versions temporarily masked by KEYWORDS for which the USE settings will be necessary in a future update.
This is fixed in git by this commit from bug #446666: http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=ecae0c4fc46d6bc8054104a99af90bc45d4e7429
This is fixed in 2.1.11.35 and 2.2.0_alpha146.