Interrupting readProcess doesn't work

The following program should terminate in 1 second, but it does not:

import System.Process
import System.Timeout

main = timeout 1000000 $ print =<< readProcess "sleep" ["2h"] ""

The problem is in the exception handler in readProcess. When it receives an asynchronous exception, it tries to clean up by closing the pipes. However the attempt to close outh blocks because the reader thread (reading with hGetContents) is blocking on the handle.

Trac metadata

Trac field	Value
Version	7.6.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
Test case
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Blocking
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Architecture