3 days spent redoing the Android autobuilder! The new version of yesod-routes generates TH splices that break the EvilSplicer. So after updating everything to new versions for the Nth time, I instead went back to older versions. The autobuilder now uses Debian jessie, instead of wheezy. And all haskell packages are pinned to use the same version as in jessie, rather than the newest versions. Since jessie is quite near to being frozen, this should make the autobuilder much less prone to getting broken by new versions of haskell packages that need patches for Android.
I happened to stumble over http://hackage.haskell.org/package/setenv while doing that. This supports setting and unsetting environment variables on Windows, which I had not known a way to do from Haskell. Cleaned up several ugly corners of the Windows port using it.