Log Message:
Update to 1.2.1.3

changelog:
1.2.1.3

* Bug fix: As it turns out, moving the literal rewrite rules to simplifier
  phase 2 does not prevent competition with the `unpack` rule, which is
  also active in this phase. Unfortunately this was hidden due to a silly
  test environment mistake. Moving literal rules back to phase 1 finally
  fixes GHC Trac #10528 correctly.

1.2.1.2

* Bug fix: Run literal rewrite rules in simplifier phase 2.
  The behavior of the simplifier changed in GHC 7.10.2,
  causing these rules to fail to fire, leading to poor code generation
  and long compilation times. See
  [GHC Trac #10528](https://ghc.haskell.org/trac/ghc/ticket/10528).