[GHC] #12128: ghci cause panic on 8.0.1

[GHC]

#12128: ghci cause panic on 8.0.1
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        Reporter:  zxtx              |                Owner:  seraphime
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.0.2
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2374
       Wiki Page:                    |
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Changes (by seraphime):

 * differential:   => Phab:D2374


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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12128#comment:6>
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