devtest fails to build ramdisk on Fedora or CentOS due to Yum multilib error

I have tried installing devtest on several Fedora 21 systems recently (last 2 weeks), and am repeatedly running into an issue where the devtest_ramdisk.sh script fails with error 1 when attempting to install PyYaml. I am using NODE_ARCH=i386, but building on an x86_64 system. Yum fails with the error "Multilib version problems found" (full error below). It also says "Protected multilib versions: PyYAML-3.11-7.fc21.x86_64 != PyYAML-3.11-6.fc21.i686".

Steps to reproduce:

1) git clone tripleo-incubator ; cd tripleo-incubator
2) export TE_DATAFILE=/home/stack/testenv.json
3) export TRIPLEO_ROOT=/home/stack/tripleo
4) export NODE_ARCH=i386
5) source scripts/devtest_variables.sh
6) devtest_setup.sh --trash-my-machine
7) devtest_testenv.sh ~/testenv.json
8) devtest_ramdisk.sh # fails with error below

Note that I did try using several different Fedora mirrors with the same behavior.

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WARNING: map-packages is deprecated. Please use the pkg-map element.
Error: Multilib version problems found. This often means that the root
       cause is something else and multilib version checking is just
       pointing out that there is a problem. Eg.:

         1. You have an upgrade for PyYAML which is missing some
            dependency that another package requires. Yum is trying to
            solve this by installing an older version of PyYAML of the
            different architecture. If you exclude the bad architecture
            yum will tell you what the root cause is (which package
            requires what). You can try redoing the upgrade with
            --exclude PyYAML.otherarch ... this should give you an error
            message showing the root cause of the problem.

         2. You have multiple architectures of PyYAML installed, but
            yum can only see an upgrade for one of those architectures.
            If you don't want/need both architectures anymore then you
            can remove the one with the missing update and everything
            will work.

         3. You have duplicate versions of PyYAML installed already.
            You can use "yum check" to get yum show these errors.

       ...you can also use --setopt=protected_multilib=false to remove
       this checking, however this is almost never the correct thing to
       do as something else is very likely to go wrong (often causing
       much more problems).

       Protected multilib versions: PyYAML-3.11-7.fc21.x86_64 != PyYAML-3.11-6.fc21.i686
installing PyYAML from svc-map
installing PyYAML from svc-map
installing redhat-lsb-core from redhat-common
installing gettext from redhat-common
installing grub2-tools from redhat-common
installing system-logos from redhat-common
installing os-prober from redhat-common
installing redhat-lsb-core from redhat-common
installing gettext from redhat-common
installing grub2-tools from redhat-common
installing system-logos from redhat-common
installing os-prober from redhat-common
install failed with error Running install-packages install. Package list: PyYAML

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