During some of the testing for centos7 (and in the process cleaning up some things for c6 as well), we noticed that there are a number of packages that are excluded from epel when using the priorities plugin with yum.

While none of the packages is a duplicate for something in base/updates, I would imagine they're marked because they provide a common directory, such as python's site-packages/ or similar. I'm not sure how much of a concern this would be, but it may be worth some investigation. There's a much smaller list for c7 as well, but I don't believe that's worth discussing yet as several are overlapping packages that have been (or should be) marked for removal as conflicts with RH's -Extras repository.

To recreate this: Bare CentOS minimal install, fully updated.

yum install yum-plugin-priorities.noarch yum install http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

Set base, updates and extras to have a priority of 10. Set epel to have a priority of 20.

yum -d3 update

This yields the following 86 packages:

--> scl-utils-20120229-1.el6.x86_64 from epel excluded (priority) --> wxGTK-gl-2.8.12-1.el6.x86_64 from epel excluded (priority) --> perl-Perl-Critic-1.105-2.el6.noarch from epel excluded (priority) --> wxGTK-media-2.8.12-1.el6.i686 from epel excluded (priority) --> freerdp-libs-1.0.2-1.el6.x86_64 from epel excluded (priority) --> febootstrap-2.7-1.el6.x86_64 from epel excluded (priority) --> snappy-devel-1.0.5-1.el6.x86_64 from epel excluded (priority) --> bakefile-0.2.8-3.el6.x86_64 from epel excluded (priority) --> python-krbV-1.0.90-1.el6.x86_64 from epel excluded (priority) --> python-tw-forms-0.9.9-3.el6.noarch from epel excluded (priority) --> scl-utils-build-20120229-1.el6.x86_64 from epel excluded (priority) --> perl-Locale-PO-0.21-2.1.el6.noarch from epel excluded (priority) --> wordnet-3.0-13.el6.i686 from epel excluded (priority) --> perl-XML-Writer-0.606-6.el6.noarch from epel excluded (priority) --> PyPAM-0.5.0-11.el6.x86_64 from epel excluded (priority) --> xhtml2ps-1.0-0.4.b5.el6.noarch from epel excluded (priority) --> osutil-1.3.1-3.el6.1.x86_64 from epel excluded (priority) --> ht2html-2.0-10.el6.noarch from epel excluded (priority) --> emacs-a2ps-4.14-10.1.el6.x86_64 from epel excluded (priority) --> perl-Config-Simple-4.59-5.el6.noarch from epel excluded (priority) --> perl-MIME-Lite-3.027-2.el6.noarch from epel excluded (priority) --> perl-Class-Accessor-0.31-0.6.1.el6.noarch from epel excluded (priority) --> python-suds-0.4.1-1.el6.noarch from epel excluded (priority) --> wxGTK-media-2.8.12-1.el6.x86_64 from epel excluded (priority) --> perl-IPC-Run-0.84-1.el6.noarch from epel excluded (priority) --> snappy-devel-1.0.5-1.el6.i686 from epel excluded (priority) --> html2ps-1.0-0.4.b5.el6.noarch from epel excluded (priority) --> freerdp-devel-1.0.2-1.el6.i686 from epel excluded (priority) --> wxBase-2.8.12-1.el6.i686 from epel excluded (priority) --> perl-DateTime-Format-DateParse-0.05-4.el6.noarch from epel excluded (priority) --> freerdp-libs-1.0.2-1.el6.i686 from epel excluded (priority) --> perl-Term-ProgressBar-2.09-8.el6.noarch from epel excluded (priority) --> scons-2.0.1-1.el6.noarch from epel excluded (priority) --> freerdp-1.0.2-1.el6.x86_64 from epel excluded (priority) --> perl-PadWalker-1.9-1.el6.x86_64 from epel excluded (priority) --> wxBase-2.8.12-1.el6.x86_64 from epel excluded (priority) --> a2ps-4.14-10.1.el6.x86_64 from epel excluded (priority) --> perl-Test-Memory-Cycle-1.04-7.1.el6.noarch from epel excluded (priority) --> snappy-1.0.5-1.el6.x86_64 from epel excluded (priority) --> wxGTK-devel-2.8.12-1.el6.x86_64 from epel excluded (priority) --> pexpect-2.3-5.el6.noarch from epel excluded (priority) --> perl-Exception-Class-1.29-1.1.el6.noarch from epel excluded (priority) --> python-ipaddr-2.1.10-2.el6.noarch from epel excluded (priority) --> a2ps-4.14-10.1.el6.i686 from epel excluded (priority) --> xerces-c-3.0.1-0.20.1.el6.x86_64 from epel excluded (priority) --> wxGTK-gl-2.8.12-1.el6.i686 from epel excluded (priority) --> python-empy-3.3-5.el6.noarch from epel excluded (priority) --> perl-Parse-RecDescent-1.965-1.el6.noarch from epel excluded (priority) --> perl-File-pushd-1.00-0.3.1.el6.noarch from epel excluded (priority) --> pki-symkey-1.3.2-3.el6.1.x86_64 from epel excluded (priority) --> xerces-c-doc-3.0.1-0.20.1.el6.noarch from epel excluded (priority) --> perl-Class-Trigger-0.13-2.1.el6.noarch from epel excluded (priority) --> perl-Net-SMTP-SSL-1.01-4.el6.noarch from epel excluded (priority) --> perl-XML-TokeParser-0.05-2.1.el6.noarch from epel excluded (priority) --> snappy-1.0.5-1.el6.i686 from epel excluded (priority) --> emacs-a2ps-el-4.14-10.1.el6.x86_64 from epel excluded (priority) --> perl-Locale-Maketext-Gettext-1.27-12.el6.noarch from epel excluded (priority) --> perl-HTML-Format-2.04-11.1.el6.noarch from epel excluded (priority) --> wordnet-3.0-13.el6.x86_64 from epel excluded (priority) --> wordnet-devel-3.0-13.el6.i686 from epel excluded (priority) --> freerdp-devel-1.0.2-1.el6.x86_64 from epel excluded (priority) --> perl-IO-Tty-1.08-3.el6.x86_64 from epel excluded (priority) --> perl-UNIVERSAL-can-1.15-1.el6.noarch from epel excluded (priority) --> perl-MIME-Types-1.28-2.el6.noarch from epel excluded (priority) --> perl-Module-Find-0.08-3.el6.noarch from epel excluded (priority) --> perl-Devel-Cycle-1.10-3.1.el6.noarch from epel excluded (priority) --> xerces-c-devel-3.0.1-0.20.1.el6.i686 from epel excluded (priority) --> perl-Pod-Spell-1.01-6.1.el6.noarch from epel excluded (priority) --> perl-String-Format-1.15-2.1.el6.noarch from epel excluded (priority) --> xerces-c-devel-3.0.1-0.20.1.el6.x86_64 from epel excluded (priority) --> wordnet-devel-3.0-13.el6.x86_64 from epel excluded (priority) --> perl-Font-AFM-1.20-3.1.el6.noarch from epel excluded (priority) --> lzop-1.02-0.9.rc1.el6.x86_64 from epel excluded (priority) --> wxGTK-2.8.12-1.el6.i686 from epel excluded (priority) --> xerces-c-3.0.1-0.20.1.el6.i686 from epel excluded (priority) --> perl-Test-Perl-Critic-1.01-7.1.el6.noarch from epel excluded (priority) --> wxGTK-devel-2.8.12-1.el6.i686 from epel excluded (priority) --> wxGTK-2.8.12-1.el6.x86_64 from epel excluded (priority) --> perl-Class-MethodMaker-2.15-2.el6.x86_64 from epel excluded (priority) --> python-urwid-0.9.9.1-1.el6.x86_64 from epel excluded (priority) --> perl-Test-Spelling-0.11-5.1.el6.noarch from epel excluded (priority) --> perl-Class-Data-Inheritable-0.08-0.3.1.el6.noarch from epel excluded (priority) --> freerdp-plugins-1.0.2-1.el6.x86_64 from epel excluded (priority) --> perl-Syntax-Highlight-Engine-Kate-0.04-5.1.el6.noarch from epel excluded (priority) --> perl-UNIVERSAL-isa-1.03-1.el6.noarch from epel excluded (priority) --> perl-B-Keywords-1.09-3.1.el6.noarch from epel excluded (priority)