[haskeline] #92: Double-check that undo works correctly with tab completion

[haskeline]

#92: Double-check that undo works correctly with tab completion
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Reporter:  judah  |       Owner:       
    Type:  task   |      Status:  new  
Priority:  minor  |   Milestone:  0.6.2
 Version:  0.6    |    Keywords:       
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 Double-check that undo works correctly with tab completion.  Specifically,
 we shouldn't be polluting the undo stack unnecessarily.

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Ticket URL: <http://trac.haskell.org/haskeline/ticket/92>
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