I am also stuck.


============
$ emerge -avuND --backtrack=400 world

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

Calculating dependencies... done!
[ebuild     U  ] dev-lang/go-1.4.1 [1.4] 10,666 KiB
[ebuild     U  ] sys-apps/busybox-1.23.1-r1 [1.23.0-r1] USE="ipv6 pam static -debug -livecd -make-symlinks -math -mdev -savedconfig (-selinux) -sep-usr -syslog -systemd" 2,200 KiB
[ebuild     U  ] dev-lang/perl-5.20.1-r4:0/5.20 [5.18.2-r2:0/5.18] USE="berkdb gdbm -debug -doc -ithreads" 13,370 KiB
[ebuild     U  ] virtual/perl-MIME-Base64-3.140.0-r1 [3.130.0-r4] 0 KiB
[ebuild     U  ] virtual/perl-IO-Compress-2.64.0 [2.60.0-r1] 0 KiB
[ebuild     U  ] virtual/perl-Compress-Raw-Zlib-2.65.0 [2.60.0-r2] 0 KiB
[ebuild     U  ] virtual/perl-IO-1.310.0 [1.280.0-r1] 0 KiB
[ebuild     U  ] virtual/perl-Sys-Syslog-0.330.0-r1 [0.320.0-r2] 0 KiB
[ebuild     U  ] virtual/perl-Encode-2.600.0 [2.490.0-r2] 0 KiB
[ebuild     U  ] virtual/perl-Scalar-List-Utils-1.380.0 [1.270.0-r2] 0 KiB
[ebuild  N     ] virtual/perl-File-Spec-3.480.0  0 KiB
[ebuild     U  ] virtual/perl-Storable-2.490.0 [2.410.0-r1] 0 KiB
[ebuild     U  ] virtual/perl-IPC-Cmd-0.920.0 [0.800.0-r1] 0 KiB
[ebuild     U  ] virtual/perl-ExtUtils-CBuilder-0.280.217 [0.280.210-r1] 0 KiB
[ebuild     U  ] virtual/perl-Params-Check-0.380.0-r1 [0.360.0-r1] 0 KiB
[ebuild     U  ] virtual/perl-Module-Metadata-1.0.19 [1.0.11-r1] 0 KiB
[ebuild     U  ] virtual/perl-version-0.990.900 [0.990.200-r1] 0 KiB
[ebuild     U  ] virtual/perl-Perl-OSType-1.7.0 [1.3.0-r1] 0 KiB
[ebuild     U  ] net-dns/bind-tools-9.10.1_p1 [9.9.5] USE="ipv6 readline ssl urandom -doc -gost -gssapi -idn -xml" 8,161 KiB
[ebuild     U  ] virtual/perl-ExtUtils-ParseXS-3.240.0 [3.180.0-r2] 0 KiB
[ebuild     U  ] virtual/perl-Module-Load-0.320.0 [0.240.0-r1] 0 KiB
[ebuild  N     ] virtual/perl-Module-CoreList-5.20.1  0 KiB
[ebuild     U  ] virtual/perl-JSON-PP-2.272.30 [2.272.20-r1] 0 KiB
[ebuild     U  ] virtual/perl-CPAN-Meta-Requirements-2.125.0-r1 [2.122.0-r2] 0 KiB
[ebuild  N     ] virtual/perl-Compress-Raw-Bzip2-2.64.0  0 KiB
[ebuild     U  ] virtual/perl-Digest-MD5-2.530.0-r2 [2.520.0-r2] 0 KiB
[uninstall     ] perl-core/Digest-MD5-2.520.0-r1
[blocks b      ] <perl-core/Digest-MD5-2.530.0 ("<perl-core/Digest-MD5-2.530.0" is blocking virtual/perl-Digest-MD5-2.530.0-r2)
[ebuild  N     ] virtual/perl-Parse-CPAN-Meta-1.441.400  0 KiB
[uninstall     ] perl-core/Parse-CPAN-Meta-1.440.400-r1
[blocks b      ] <perl-core/Parse-CPAN-Meta-1.441.400 ("<perl-core/Parse-CPAN-Meta-1.441.400" is blocking virtual/perl-Parse-CPAN-Meta-1.441.400)
[ebuild     U  ] virtual/perl-CPAN-Meta-YAML-0.12.0 [0.8.0-r2] 0 KiB
[uninstall     ] perl-core/CPAN-Meta-YAML-0.8.0-r1
[blocks b      ] <perl-core/CPAN-Meta-YAML-0.12.0 ("<perl-core/CPAN-Meta-YAML-0.12.0" is blocking virtual/perl-CPAN-Meta-YAML-0.12.0)
[ebuild     U  ] virtual/perl-Digest-SHA-5.880.0 [5.820.0] 0 KiB
[uninstall     ] perl-core/Digest-SHA-5.820.0
[blocks b      ] <perl-core/Digest-SHA-5.880.0 ("<perl-core/Digest-SHA-5.880.0" is blocking virtual/perl-Digest-SHA-5.880.0)
[ebuild  N     ] perl-core/libnet-1.270.0  USE="-sasl" 68 KiB
[ebuild     U  ] virtual/perl-libnet-1.270.0 [1.220.0-r3] 0 KiB
[blocks b      ] >perl-core/libnet-1.220.0-r999 (">perl-core/libnet-1.220.0-r999" is blocking virtual/perl-libnet-1.220.0-r3)
[blocks B      ] <perl-core/Sys-Syslog-0.330.0 ("<perl-core/Sys-Syslog-0.330.0" is blocking virtual/perl-Sys-Syslog-0.330.0-r1)
[blocks B      ] <perl-core/Scalar-List-Utils-1.380.0 ("<perl-core/Scalar-List-Utils-1.380.0" is blocking virtual/perl-Scalar-List-Utils-1.380.0)
[blocks B      ] <perl-core/ExtUtils-ParseXS-3.240.0 ("<perl-core/ExtUtils-ParseXS-3.240.0" is blocking virtual/perl-ExtUtils-ParseXS-3.240.0)
[blocks B      ] <perl-core/Params-Check-0.380.0 ("<perl-core/Params-Check-0.380.0" is blocking virtual/perl-Params-Check-0.380.0-r1)
[blocks B      ] <perl-core/CPAN-Meta-Requirements-2.125.0 ("<perl-core/CPAN-Meta-Requirements-2.125.0" is blocking virtual/perl-CPAN-Meta-Requirements-2.125.0-r1)
[blocks B      ] <perl-core/Compress-Raw-Bzip2-2.64.0 ("<perl-core/Compress-Raw-Bzip2-2.64.0" is blocking virtual/perl-Compress-Raw-Bzip2-2.64.0)
[blocks B      ] <perl-core/Module-Load-0.320.0 ("<perl-core/Module-Load-0.320.0" is blocking virtual/perl-Module-Load-0.320.0)
[blocks B      ] <perl-core/Compress-Raw-Zlib-2.65.0 ("<perl-core/Compress-Raw-Zlib-2.65.0" is blocking virtual/perl-Compress-Raw-Zlib-2.65.0)
[blocks B      ] <perl-core/Module-Metadata-1.0.19 ("<perl-core/Module-Metadata-1.0.19" is blocking virtual/perl-Module-Metadata-1.0.19)
[blocks B      ] <perl-core/File-Spec-3.480.0 ("<perl-core/File-Spec-3.480.0" is blocking virtual/perl-File-Spec-3.480.0)
[blocks B      ] <perl-core/IO-Compress-2.64.0 ("<perl-core/IO-Compress-2.64.0" is blocking virtual/perl-IO-Compress-2.64.0)

Total: 31 packages (26 upgrades, 5 new, 4 uninstalls), Size of downloads: 34,463 KiB
Conflict: 16 blocks (11 unsatisfied)

!!! Multiple package instances within a single package slot have been pulled
!!! into the dependency graph, resulting in a slot conflict:

dev-lang/perl:0

  (dev-lang/perl-5.20.1-r4:0/5.20::gentoo, ebuild scheduled for merge) pulled in by
    =dev-lang/perl-5.20* required by (virtual/perl-CPAN-Meta-Requirements-2.125.0-r1:0/0::gentoo, ebuild scheduled for merge)
    ^              ^^^^^
    (and 27 more with the same problem)

  (dev-lang/perl-5.18.2-r2:0/5.18::gentoo, installed) pulled in by
    dev-lang/perl:0/5.18=[-build(-)] required by (net-analyzer/net-snmp-5.7.3_pre5-r1:0/0::gentoo, installed)
                 ^^^^^^^^
    (and 59 more with the same problem)


It may be possible to solve this problem by using package.mask to
prevent one of those packages from being selected. However, it is also
possible that conflicting dependencies exist such that they are
impossible to satisfy simultaneously.  If such a conflict exists in
the dependencies of two different packages, then those packages can
not be installed simultaneously.

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


 * Error: The above package list contains packages which cannot be
 * installed at the same time on the same system.

  (perl-core/Scalar-List-Utils-1.270.0:0/0::gentoo, installed) pulled in by
    perl-core/Scalar-List-Utils required by @selected

  (perl-core/CPAN-Meta-Requirements-2.122.0-r1:0/0::gentoo, installed) pulled in by
    perl-core/CPAN-Meta-Requirements required by @selected

  (virtual/perl-File-Spec-3.480.0:0/0::gentoo, ebuild scheduled for merge) pulled in by
    =virtual/perl-File-Spec-3.480.0 required by (dev-perl/DBI-1.628.0:0/0::gentoo, installed)
    virtual/perl-File-Spec required by (dev-perl/DBI-1.628.0:0/0::gentoo, installed)

  (perl-core/File-Spec-3.400.0:0/0::gentoo, installed) pulled in by
    perl-core/File-Spec required by @selected

  (perl-core/IO-Compress-2.60.0:0/0::gentoo, installed) pulled in by
    perl-core/IO-Compress required by @selected

  (perl-core/Compress-Raw-Zlib-2.60.0:0/0::gentoo, installed) pulled in by
    perl-core/Compress-Raw-Zlib required by @selected

  (perl-core/Compress-Raw-Bzip2-2.60.0:0/0::gentoo, installed) pulled in by
    perl-core/Compress-Raw-Bzip2 required by @selected

  (perl-core/Module-Load-0.240.0:0/0::gentoo, installed) pulled in by
    perl-core/Module-Load required by @selected

  (perl-core/ExtUtils-ParseXS-3.180.0-r1:0/0::gentoo, installed) pulled in by
    perl-core/ExtUtils-ParseXS required by @selected

  (virtual/perl-CPAN-Meta-Requirements-2.125.0-r1:0/0::gentoo, ebuild scheduled for merge) pulled in by
    =virtual/perl-CPAN-Meta-Requirements-2.125.0-r1 required by (perl-core/CPAN-Meta-2.120.921-r1:0/0::gentoo, installed)
    >=virtual/perl-CPAN-Meta-Requirements-2.121.0 required by (perl-core/CPAN-Meta-2.120.921-r1:0/0::gentoo, installed)

  (virtual/perl-Module-Load-0.320.0:0/0::gentoo, ebuild scheduled for merge) pulled in by
    >=virtual/perl-Module-Load-0.12 required by (perl-core/Module-Load-Conditional-0.540.0:0/0::gentoo, installed)
    =virtual/perl-Module-Load-0.320.0 required by (perl-core/Module-Load-Conditional-0.540.0:0/0::gentoo, installed)
    virtual/perl-Module-Load required by @selected

  (perl-core/Sys-Syslog-0.320.0-r1:0/0::gentoo, installed) pulled in by
    perl-core/Sys-Syslog required by @selected

  (virtual/perl-Sys-Syslog-0.330.0-r1:0/0::gentoo, ebuild scheduled for merge) pulled in by
    virtual/perl-Sys-Syslog required by @selected
    =virtual/perl-Sys-Syslog-0.330.0-r1 required by (dev-perl/DBI-1.628.0:0/0::gentoo, installed)
    >=virtual/perl-Sys-Syslog-0.170.0 required by (dev-perl/DBI-1.628.0:0/0::gentoo, installed)

  (virtual/perl-IO-Compress-2.64.0:0/0::gentoo, ebuild scheduled for merge) pulled in by
    virtual/perl-IO-Compress required by (dev-perl/Net-HTTP-6.60.0:0/0::gentoo, installed)
    =virtual/perl-IO-Compress-2.64.0 required by (perl-core/IO-Zlib-1.100.0:0/0::gentoo, installed)
    virtual/perl-IO-Compress required by @selected
    =virtual/perl-IO-Compress-2.64.0 required by (dev-perl/Net-HTTP-6.60.0:0/0::gentoo, installed)
    virtual/perl-IO-Compress required by (perl-core/IO-Zlib-1.100.0:0/0::gentoo, installed)
    >=virtual/perl-IO-Compress-2.021 required by (dev-perl/HTTP-Message-6.30.0-r1:0/0::gentoo, installed)
    =virtual/perl-IO-Compress-2.64.0 required by (dev-perl/HTTP-Message-6.30.0-r1:0/0::gentoo, installed)

  (virtual/perl-ExtUtils-ParseXS-3.240.0:0/0::gentoo, ebuild scheduled for merge) pulled in by
    virtual/perl-ExtUtils-ParseXS required by @selected

  (virtual/perl-Module-Metadata-1.0.19:0/0::gentoo, ebuild scheduled for merge) pulled in by
    >=virtual/perl-Module-Metadata-1.0.5 required by (perl-core/Module-Load-Conditional-0.540.0:0/0::gentoo, installed)
    virtual/perl-Module-Metadata required by @selected
    =virtual/perl-Module-Metadata-1.0.19 required by (perl-core/Module-Load-Conditional-0.540.0:0/0::gentoo, installed)

  (perl-core/Params-Check-0.360.0-r1:0/0::gentoo, installed) pulled in by
    perl-core/Params-Check required by @selected

  (virtual/perl-Scalar-List-Utils-1.380.0:0/0::gentoo, ebuild scheduled for merge) pulled in by
    =virtual/perl-Scalar-List-Utils-1.380.0 required by (perl-core/CPAN-Meta-2.120.921-r1:0/0::gentoo, installed)
    virtual/perl-Scalar-List-Utils required by (perl-core/CPAN-Meta-2.120.921-r1:0/0::gentoo, installed)
    virtual/perl-Scalar-List-Utils required by (dev-perl/IO-Socket-SSL-1.967.0:0/0::gentoo, installed)
    =virtual/perl-Scalar-List-Utils-1.380.0 required by (dev-perl/IO-Socket-SSL-1.967.0:0/0::gentoo, installed)
    virtual/perl-Scalar-List-Utils required by (perl-core/CPAN-Meta-Requirements-2.122.0-r1:0/0::gentoo, installed)
    =virtual/perl-Scalar-List-Utils-1.380.0 required by (perl-core/IO-Compress-2.60.0:0/0::gentoo, installed)
    =virtual/perl-Scalar-List-Utils-1.380.0 required by (perl-core/CPAN-Meta-Requirements-2.122.0-r1:0/0::gentoo, installed)
    virtual/perl-Scalar-List-Utils required by (perl-core/IO-Compress-2.60.0:0/0::gentoo, installed)

  (virtual/perl-Params-Check-0.380.0-r1:0/0::gentoo, ebuild scheduled for merge) pulled in by
    virtual/perl-Params-Check required by @selected
    =virtual/perl-Params-Check-0.380.0-r1 required by (perl-core/Module-Load-Conditional-0.540.0:0/0::gentoo, installed)
    virtual/perl-Params-Check required by (perl-core/Module-Load-Conditional-0.540.0:0/0::gentoo, installed)

  (virtual/perl-Compress-Raw-Zlib-2.65.0:0/0::gentoo, ebuild scheduled for merge) pulled in by
    virtual/perl-Compress-Raw-Zlib required by (dev-perl/Net-HTTP-6.60.0:0/0::gentoo, installed)
    =virtual/perl-Compress-Raw-Zlib-2.65.0 required by (dev-perl/HTTP-Message-6.30.0-r1:0/0::gentoo, installed)
    =virtual/perl-Compress-Raw-Zlib-2.65.0 required by (dev-perl/Net-HTTP-6.60.0:0/0::gentoo, installed)
    virtual/perl-Compress-Raw-Zlib required by @selected
    virtual/perl-Compress-Raw-Zlib required by (dev-perl/HTTP-Message-6.30.0-r1:0/0::gentoo, installed)
    >=virtual/perl-Compress-Raw-Zlib-2.60.0 required by (perl-core/IO-Compress-2.60.0:0/0::gentoo, installed)
    =virtual/perl-Compress-Raw-Zlib-2.65.0 required by (perl-core/IO-Compress-2.60.0:0/0::gentoo, installed)

  (perl-core/Module-Metadata-1.0.11-r1:0/0::gentoo, installed) pulled in by
    perl-core/Module-Metadata required by @selected


For more information about Blocked Packages, please refer to the following
section of the Gentoo Linux x86 Handbook (architecture is irrelevant):

http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?full=1#blocked

============

$ eix net-analyzer/net-snmp                                                                                                                                                                                         1 ?
[I] net-analyzer/net-snmp
     Available versions:  5.7.3_pre5-r1^t ~5.7.3_pre5-r2^t ~5.7.3_pre5-r3^t {X bzip2 doc elf ipv6 lm_sensors mfd-rewrites minimal mysql netlink pci perl python rpm selinux ssl tcpd ucd-compat zlib PYTHON_TARGETS="python2_7"}
     Installed versions:  5.7.3_pre5-r1^t(10:41:23 AM 11/10/2014)(bzip2 ipv6 mysql perl python ssl tcpd zlib -X -doc -elf -lm_sensors -mfd-rewrites -minimal -netlink -pci -rpm -selinux -ucd-compat PYTHON_TARGETS="python2_7")
     Homepage:            http://net-snmp.sourceforge.net/
     Description:         Software for generating and retrieving SNMP data


============

$  for name in $(qlist -IC 'perl-core/*') ; do equery depends $name ; done                                                                                                                                           1 ?
 * These packages depend on perl-core/Archive-Tar:
virtual/perl-Archive-Tar-1.900.0-r2 (~perl-core/Archive-Tar-1.900.0)
 * These packages depend on perl-core/Compress-Raw-Bzip2:
 * These packages depend on perl-core/Compress-Raw-Zlib:
virtual/perl-Compress-Raw-Zlib-2.60.0-r2 (~perl-core/Compress-Raw-Zlib-2.60.0)
 * These packages depend on perl-core/CPAN-Meta:
virtual/perl-CPAN-Meta-2.120.921-r2 (~perl-core/CPAN-Meta-2.120.921)
 * These packages depend on perl-core/CPAN-Meta-Requirements:
virtual/perl-CPAN-Meta-Requirements-2.122.0-r2 (~perl-core/CPAN-Meta-Requirements-2.122.0)
 * These packages depend on perl-core/CPAN-Meta-YAML:
virtual/perl-CPAN-Meta-YAML-0.8.0-r2 (~perl-core/CPAN-Meta-YAML-0.8.0)
 * These packages depend on perl-core/Data-Dumper:
virtual/perl-Data-Dumper-2.154.0 (~perl-core/Data-Dumper-2.154.0)
 * These packages depend on perl-core/Digest:
virtual/perl-Digest-1.170.0-r4 (~perl-core/Digest-1.170.0)
 * These packages depend on perl-core/Digest-MD5:
virtual/perl-Digest-MD5-2.520.0-r2 (~perl-core/Digest-MD5-2.520.0)
 * These packages depend on perl-core/Digest-SHA:
virtual/perl-Digest-SHA-5.820.0 (~perl-core/Digest-SHA-5.820.0)
 * These packages depend on perl-core/ExtUtils-ParseXS:
virtual/perl-ExtUtils-ParseXS-3.180.0-r2 (~perl-core/ExtUtils-ParseXS-3.180.0)
 * These packages depend on perl-core/File-Spec:
 * These packages depend on perl-core/File-Temp:
virtual/perl-File-Temp-0.230.400-r2 (~perl-core/File-Temp-0.230.400)
 * These packages depend on perl-core/IO-Compress:
virtual/perl-IO-Compress-2.60.0-r1 (~perl-core/IO-Compress-2.60.0)
 * These packages depend on perl-core/IO-Zlib:
virtual/perl-IO-Zlib-1.100.0-r4 (~perl-core/IO-Zlib-1.100.0)
 * These packages depend on perl-core/Module-Build:
virtual/perl-Module-Build-0.400.300-r1 (~perl-core/Module-Build-0.400.300)
 * These packages depend on perl-core/Module-Load:
virtual/perl-Module-Load-0.240.0-r1 (~perl-core/Module-Load-0.240.0)
 * These packages depend on perl-core/Module-Load-Conditional:
 * These packages depend on perl-core/Module-Metadata:
virtual/perl-Module-Metadata-1.0.11-r1 (~perl-core/Module-Metadata-1.0.11)
 * These packages depend on perl-core/Params-Check:
virtual/perl-Params-Check-0.360.0-r1 (~perl-core/Params-Check-0.360.0)
 * These packages depend on perl-core/Parse-CPAN-Meta:
 * These packages depend on perl-core/Scalar-List-Utils:
virtual/perl-Scalar-List-Utils-1.270.0-r2 (~perl-core/Scalar-List-Utils-1.270.0)
 * These packages depend on perl-core/Sys-Syslog:
virtual/perl-Sys-Syslog-0.320.0-r2 (~perl-core/Sys-Syslog-0.320.0)
 * These packages depend on perl-core/Test-Harness:
virtual/perl-Test-Harness-3.260.0-r2 (~perl-core/Test-Harness-3.260.0)
 * These packages depend on perl-core/Time-Local:
virtual/perl-Time-Local-1.230.0-r1 (~perl-core/Time-Local-1.230.0)

============