Team Build 2015 run script if build fails

Hi,

I'm new to CI. I'm setting up our projects to build in the new Team Build 2015. I Love it! I would think running a power-shell script if the build fails would be a simple thing, but I can not figure out how to do this.

I do see how to set a build step to 'always run' so it runs even if the build fails, but then I don't see any environment variables I can use to conditionally do things if the build fails.

Any help would be very much appreciated. Thanks.

-Damon