Yum Dependency (Transaction check) error when using custom repository

Issue

Package update/installation fails with dependency/transaction error, e. g.:

On a x86_64 system, yum is trying to install an i686 package:

# yum install openssl-devel
<...>
--> Running transaction check
---> Package libcom_err.i686 0:1.41.12-21.el6 will be installed
--> Processing Dependency: ld-linux.so.2(GLIBC_2.3) for package: libcom_err-1.41.12-21.el6.i686
<...>
---> Package libsepol-devel.x86_64 0:2.0.41-4.el6 will be installed
--> Running transaction check
---> Package glibc.i686 0:2.12-1.166.el6_7.7 will be installed
--> Processing Dependency: libfreebl3.so(NSSRAWHASH_3.12.3) for package: glibc-2.12-1.166.el6_7.7.i686
--> Processing Dependency: libfreebl3.so for package: glibc-2.12-1.166.el6_7.7.i686
--> Running transaction check
---> Package nss-softokn-freebl.i686 0:3.14.3-23.el6_7 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================================================================================================
 Package                                Arch                      Version                               Repository                                      Size
=============================================================================================================================================================
Installing:
 openssl-devel                          x86_64                    1.0.1e-48.el6_8.1                     rhel6-custom-channel-to-date                    1.2 M
Installing for dependencies:
 glibc                                  i686                      2.12-1.166.el6_7.7                    rhel6-custom-channel-to-date                    4.3 M
 keyutils-libs-devel                    x86_64                    1.4-5.el6                             rhel6-custom-channel-to-date                     29 k
 krb5-devel                             x86_64                    1.10.3-42z1.el6_7                     rhel6-custom-channel-to-date                    502 k
 libcom_err                             i686                      1.41.12-21.el6                        rhel6-custom-channel-to-date                     37 k
 libcom_err-devel                       x86_64                    1.41.12-21.el6                        rhel6-custom-channel-to-date                     32 k
 libselinux-devel                       x86_64                    2.0.94-5.8.el6                        rhel6-custom-channel-to-date                    137 k
 libsepol-devel                         x86_64                    2.0.41-4.el6                          rhel6-custom-channel-to-date                     64 k
 nss-softokn-freebl                     i686                      3.14.3-23.el6_7                       rhel6-custom-channel-to-date                    157 k
 zlib-devel                             x86_64                    1.2.3-29.el6                          rhel6-custom-channel-to-date                     44 k

Transaction Summary
=============================================================================================================================================================
Install      10 Package(s)

Total size: 6.5 M
Installed size: 18 M
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test


Transaction Check Error:
  package libcom_err-1.41.12-22.el6.x86_64 (which is newer than libcom_err-1.41.12-21.el6.i686) is already installed