GHCi does not always detect when modules become stale during compilation

Here is a conceived example that illustrates the issue.

File Foo.hs is changed after it's content has been read in the Haskell pre-processor phase.

{{{ #!/bin/bash # # file preprocess.sh # cat $2 > $3 sleep 1 touch $1 }}}

-- file Foo.hs
{-# OPTIONS_GHC -F -pgmF ./preprocess.sh #-}
module Foo where

$ ghci Foo.hs
*Foo> :reload

Expected result: Foo.hs is recompiled on :reload

Actual result: Nothing is recompiled on :reload

Trac metadata

Trac field	Value
Version	7.4.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
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