Give 6.8-branch output for TH_fail

testsuite/tests/ghc-regress/th/TH_fail-6.8.stderr

+
+TH_fail.hs:1:0: Code not written yet...

testsuite/tests/ghc-regress/th/all.T

@@ -76,7 +76,7 @@ test('TH_dataD1', normal, compile_fail, ['-v0'])
 
 test('TH_ppr1', normal, compile_and_run, ['-fglasgow-exts'])
 
-test('TH_fail', normal, compile_fail, ['-v0'])
+test('TH_fail', if_compiler_lt('ghc','6.9', namebase('TH_fail-6.8')), compile_fail, ['-v0'])
 test('TH_scopedTvs', normal, compile_fail, ['-v0'])
 
 test('TH_runIO', if_compiler_lt('ghc','6.9', namebase('TH_runIO-6.8')), compile_fail, ['-v0'])