fix an unexpected pass

testsuite/tests/concurrent/should_run/all.T

@@ -36,7 +36,7 @@ test('4030', omit_ways('ghci'), compile_and_run, ['-O'])
 # each of these runs for about a second
 test('throwto001', [reqlib('random'), extra_run_opts('1000 2000')],
                    compile_and_run, [''])
-test('throwto002', [reqlib('random'), ignore_output], compile_and_run, [''])
+test('throwto002', [reqlib('random')], compile_and_run, [''])
 test('throwto003', normal, compile_and_run, [''])
 
 test('mask001', normal, compile_and_run, [''])

testsuite/tests/concurrent/should_run/throwto002.hs

@@ -15,7 +15,7 @@ main = do
     t1 <- block $ forkIO (thread r t2)
     t2 <- block $ forkIO (thread r t1)
   threadDelay 1000000
-  readIORef r >>= print
+  readIORef r >>= print . (/= 0)
 
 thread r t = run
   where 

testsuite/tests/concurrent/should_run/throwto002.stdout

+True