archive of old ghc nightly builds?

I'm looking for an archive of ghc nightly builds, so I can bisect a suspected bug at least to a small date range.  Does such an archive exist?  I have colleagues who say they used such an archive, and fairly recently, but we can't seem to find it from the ghc dev wiki today.  The date range I am hoping for is roughly Sept 2012 to April 2014. Regards, Malcolm