These are the packages that would be merged, in order:

Calculating dependencies  ... done!

!!! One or more updates have been skipped due to a dependency conflict:

dev-db/mysql:0

  (dev-db/mysql-5.5.14::gentoo, ebuild scheduled for merge) conflicts with
    =dev-db/mysql-5.1*[-embedded,-minimal,-static] required by (virtual/mysql-5.1::gentoo, ebuild scheduled for merge)

[ebuild  N     ] dev-db/mysql-init-scripts-1.2  0 kB
[ebuild  N     ] dev-perl/Net-Daemon-0.43  28 kB
[ebuild  NS    ] sys-devel/autoconf-2.13 [2.65-r1] 434 kB
[ebuild  N     ] media-libs/audiofile-0.2.7  USE="-static-libs" 491 kB
[ebuild  N     ] app-admin/eselect-ctags-1.13  8 kB
[ebuild  N     ] perl-core/Storable-2.20  174 kB
[ebuild  N     ] perl-core/File-Spec-3.31  132 kB
[ebuild  N     ] virtual/perl-Sys-Syslog-0.270.0-r1  0 kB
[ebuild  N     ] app-admin/eselect-emacs-1.13  0 kB
[ebuild  N     ] virtual/perl-Storable-2.20  0 kB
[ebuild  N     ] virtual/perl-File-Spec-3.31  0 kB
[ebuild  N     ] dev-perl/PlRPC-0.202.0  18 kB
[ebuild  N     ] dev-perl/DBI-1.615  USE="-test" 558 kB
[ebuild  N     ] app-editors/xemacs-21.4.22-r1  USE="X berkdb gdbm gif gpm jpeg png -Xaw3d -athena -canna -dnd -eolconv -esd -freewnn -ldap -motif -mule -nas -neXt -pop -postgres -tiff -xface -xim" 8,201 kB
[ebuild  N     ] app-xemacs/xemacs-base-2.27  524 kB
[ebuild  N     ] app-xemacs/emerge-1.11  60 kB
[ebuild  N    #] dev-db/mysql-5.1.58-r1  USE="berkdb community perl ssl -big-tables -cluster -debug -embedded -extraengine -latin1 -max-idx-128 -minimal -pbxt -profiling (-selinux) -static -test -xtradb" 25,458 kB
[ebuild  N     ] virtual/mysql-5.1  USE="-embedded -minimal -static" 0 kB
[ebuild  N     ] dev-perl/DBD-mysql-4.01.7  130 kB

Total: 19 packages (18 new, 1 in new slot), Size of downloads: 36,213 kB

The following keyword changes are necessary to proceed:
#required by virtual/mysql-5.1, required by dev-perl/DBD-mysql-4.01.7
=dev-db/mysql-5.1.58-r1 ~amd64

The following mask changes are necessary to proceed:
#required by virtual/mysql-5.1, required by dev-perl/DBD-mysql-4.01.7
# /etc/portage/package.mask:
=dev-db/mysql-5.1.58-r1

NOTE: This --autounmask behavior can be disabled by setting
      EMERGE_DEFAULT_OPTS="--autounmask=n" in make.conf.