問題

# yum install -y xxxxx

There are unfinished transactions remaining. You might consider running yum-complete-transaction, or "yum-complete-transaction --cleanup-only" and "yum history redo last", first to finish them. If those don't work you'll have to try removing/installing packages by hand (maybe package-cleanup can help).
The program yum-complete-transaction is found in the yum-utils package.

という出力がでた。
ちょっと前にyumを途中でCtrl-Cで中断したためだ。

対処

# yum install -y yum-utils
# yum-complete-transaction --cleanup-only
Cleaning up unfinished transaction journals
Cleaning up 2015-02-19.12:51.09

これで解決