Bug 726872

enhancement request:

The customer desires the ability to be able to rollback to a last known good version of an RPM in less than four minutes across many thousands of systems, if a software bug or other deficiency is discovered post installation. To facilitate this requirement previous contents of the last known good version of the RPM must be preserved during installation of the new RPM.

Requirements:
- The rollback must be name value pair specific for the package and version and not rely upon date or time. Rolling back foobar-10.0 will revert the software to foo-9.0.

- The rollback should also rollback one-to-one dependencies if possible. Dependencies used by more than one package should not rollback. If package-a.9.0 and package-b.21.0 are both dependent on package-c.99.0 and a rollback on package-a.9.0 is requested then package-a.9.0 will rollback, package-c.99.0 will remain unchanged, and an error will be logged. If package-c.99.0 has no other linked dependencies other than package-a.9.0 then both packages will rollback. 

- Files that do not match the original MD5 signature, configuration files that can be altered post installation, for example should not be excluded from the snapshot due to a failed signature.

Assumptions:
- Command and control software is in place to issue the necessary commands to execute rollback scenarios.