They're failing consistently:
http://hydra.nixos.org/job/hydra/master/build.i686-linux/all
WOYOIGB747WCHE3M2YEIQFNHYL24NE6VIBAWNCVAX3K7VPPOR3IAC
2GYW62QSSAGBUYOJAYCD2BKNUSOET2PKVLULZCM3OS37D4Z3MKFAC
IZYR3KTL4M5OERLZM4LAC6N6TWZLQXMRVQIFOCIKMDQU3F2E7FHQC
T4LLYESZ2HUXSLKZ6GNBLVWUVG7R5IDFHYHYO773QIZ6QTOOXR2AC
WQ2VQ7H3CTHM47EOW3F3BB2OUAI7ZXX5FBBAD2DODQOFO5LRM4WAC
genAttrs' = pkgs.lib.genAttrs [ "x86_64-linux" "i686-linux" ];
genAttrs' = pkgs.lib.genAttrs [ "x86_64-linux" /* "i686-linux" */ ];