Reverting to previously installed FreeNAS build made easy?

[neubert]

Hi,

for testing purposes one has to upgrade to nightly builds of FreeNAS which may solve defects from earlier builds. But sometimes they also introduce new defects. If the these defects are severe one has to revert to the previously installed build.

This can be done using the GUI upgrade function to effectively downgrade to a previous version. I think I read that FreeNAS keeps the previously installed build on the installation medium. Thus my question: is there an easier way to revert to the previously installed version that does not involve reloading it first through the GUI?

Thanks for a hint and sorry if I should have missed the instructions although I searched forum and docs.

Boris