cabal test fails when detailed-0.9 tests change current directory

[NovaDenizen]

The cabal binary passes a relative log pathname to Distribution.Simple.Test.stubMain via stdin, stubMain runs the tests, then Test.stubWriteLog fails to write the results because the relative path is no longer valid. Cabal fails to read the log and gives the "no parse" error as below.

In this example, tests contains the setCurrentDirectory call, but it could just as easily be within a returned TestInstance.

module Fail where

import System.Directory
import Distribution.TestSuite

tests :: IO [Test]
tests = do
    setCurrentDirectory ".."
    return []

$ cabal test
Running 1 test suites...
Test suite fail: RUNNING...
cabal: Prelude.read: no parse
$ cabal -V
cabal-install version 1.16.0.2
using version 1.16.0.3 of the Cabal library

[23Skidoo]

/cc @ttuegel

[NovaDenizen]

Submitted pull request 8aacf2b