* Stack eagerly tries to parse all cabal files related to a
snapshot. Starting with Stackage Nightly 2017-07-31, snapshots are
using GHC 8.2.1, and the `ghc.cabal` file implicitly referenced uses
the (not yet supported) Cabal 2.0 file format. Future releases of
Stack will both be less eager about cabal file parsing and support
Cabal 2.0. This patch simply bypasses the error for invalid parsing.