failing to build on osx

[shmish111]

GHC84
### Failure in: 1:Round-trip tests:0:ghc710:20:Control.hs
tests/Test/Common.hs:123
Control.hs
### Failure in: 1:Round-trip tests:0:ghc710:77:Internals.hs
tests/Test/Common.hs:123
Internals.hs
Cases: 1773  Tried: 1773  Errors: 0  Failures: 2
Counts {cases = 1773, tried = 1773, errors = 0, failures = 2}
Test suite test: FAIL
Test suite logged to: dist/test/ghc-exactprint-0.5.6.1-test.log
0 of 1 test suites (0 of 1 test cases) passed.
builder for '/nix/store/0c1fmqbn8fr1xi6wilx0zdq13nx180pj-ghc-exactprint-0.5.6.1.drv' failed with exit code 1