fetchWith: resolve https://github.com/NixOS/cabal2nix/issues/150
fetchWith: resolve https://github.com/NixOS/cabal2nix/issues/150

New versions of nix-prefetch-git print an additional line, saying:

  Commit date is 2015-01-15 21:41:08 +0100

We just ignore that information.

dmalikov/cabal2nix,Fuuzetsu/cabal2nix,jb55/cabal2nix,bennofs/cabal2nix,spencerjanssen/cabal2nix,gridaphobe/cabal2nix,psibi/cabal2nix