How to merge config files interactively after "yum update"

The closest thing I've found to Gentoo's etc-update is rpmconf:

# yum install -y rpmconf    
# rpmconf -a
Configuration file `/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.25-5.b18.fc21.x86_64/jre/lib/security/US_export_policy.jar'
-rw-r--r--. 1 root root 620 Oct  2 16:38 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.25-5.b18.fc21.x86_64/jre/lib/security/US_export_policy.jar
-rw-r--r--. 1 root root 620 Dec 15 12:11 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.25-5.b18.fc21.x86_64/jre/lib/security/US_export_policy.jar.rpmnew
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ?  Your options are:
    Y or I  : install the package maintainer's version
    N or O  : keep your currently-installed version
      D     : show the differences between the versions
      M     : merge configuration files
      Z     : background this process to examine the situation
      S     : skip this file
 The default action is to keep your current version.
*** aliases (Y/I/N/O/D/Z/S) [default=N] ? 
Your choice: Y

This yum plugin adds the "--merge-conf" command line option. With this option, Yum will ask you what to do with config files which have changed on updating a package.

https://apps.fedoraproject.org/packages/yum-plugin-merge-conf

The only way I found so far is vimdiff: