I poked around and came up with a workaround that seems to take care of it on CentOS 6.7 at least:
# yum shell --disablerepo=pgdg93
remove libevent
install libevent2
run
Seems to be working fine. I was able to update one of the systems. Next time, I'll wait until after I've eaten lunch before firing off a message. Hopefully, the solution is useful to someone else.