BlockedIndefinitely not thrown when it should be

The following program demonstrates the bug. When run with no arguments, the "die" thread gets a BlockedIndefinitely exception, when run with command line arguments it does not.

module Main where
import Control.Monad
import Control.Concurrent
import Control.Concurrent.STM
import System.Environment

main :: IO ()
main = do { flags <- getArgs
           ; if (length flags > 0)
            then forkIO die >>         -- die does not die
                 threadDelay 10000000
            else die                   -- die dies         
          }

-- expect BlockedIndefinitely exception to be thrown
die :: IO ()
die = newTVarIO "die" >>= f >>= print
 where f tv = atomically $ do { x <- readTVar tv
                              ; if x == "die" then retry else return x
                              }

Trac metadata

Trac field	Value
Version	6.8.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Runtime System
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	MacOS X
Architecture	x86