Warning: RPMDB altered outside of yum

Problem:
On RedHat you get this message:
Warning: RPMDB altered outside of yum.


Example:
[root@test ~]# yum install screen
Loaded plugins: product-id, refresh-packagekit, rhnplugin, subscription-manager
Updating Red Hat repositories.
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package screen.x86_64 0:4.0.3-16.el6 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
screen x86_64 4.0.3-16.el6 rhel-x86_64-server-6 494 k

Transaction Summary
================================================================================
Install 1 Package(s)

Total download size: 494 k
Installed size: 0
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Warning: RPMDB altered outside of yum.
Installing : screen-4.0.3-16.el6.x86_64 1/1
duration: 182(ms)
Installed products updated.

Installed:
screen.x86_64 0:4.0.3-16.el6

Complete!


Solution:
Run "yum clean all"